Method and system for on-line blending of foaming agent with foam modifier for addition to cementitious slurries

ABSTRACT

Disclosed is a method and system for blending a foam modifier with foaming agent online, e.g., as may be particularly useful for gypsum or cement slurries. The foam modifier comprises a fatty alcohol that is added to a gypsum or cement slurry that includes foaming agent, such as an alkyl sulfate surfactant. The fatty alcohol can be a C 6 -C 16  fatty alcohol in some embodiments. The use of such a foam modifier can be used, for example, to stabilize the foam, reduce waste of foaming agent, improve void size control in the final product, and improve the gypsum board manufacturing process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation in part of U.S. patentapplication Ser. Nos. 15/186,320 and 15/186,336, which both were filedon Jun. 17, 2016 and claim the benefit of U.S. Provisional PatentApplication No. 62/235,979, filed Oct. 1, 2015, all of which priorapplications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Set gypsum (i.e., calcium sulfate dihydrate) is a well-known materialthat is used in many products, including panels and other products forbuilding construction and remodeling. One such panel (often referred toas gypsum board) is in the form of a set gypsum core sandwiched betweentwo cover sheets (e.g., paper-faced board) and is commonly used indrywall construction of interior walls and ceilings of buildings. One ormore dense layers, often referred to as “skim coats” may be included oneither side of the core, usually at the paper-core interface.

During manufacture of the board, stucco (i.e., calcined gypsum in theform of calcium sulfate hemihydrate and/or calcium sulfate anhydrite),water, and other ingredients as appropriate are mixed, typically in apin mixer as the term is used in the art. A slurry is formed anddischarged from the mixer onto a moving conveyor carrying a cover sheetwith one of the skim coats (if present) already applied (often upstreamof the mixer). The slurry is spread over the paper (with skim coatoptionally included on the paper). Another cover sheet, with or withoutskim coat, is applied onto the slurry to form the sandwich structure ofdesired thickness with the aid of, e.g., a forming plate or the like.The mixture is cast and allowed to harden to form set (i.e., rehydrated)gypsum by reaction of the calcined gypsum with water to form a matrix ofcrystalline hydrated gypsum (i.e., calcium sulfate dihydrate). It is thedesired hydration of the calcined gypsum that enables the formation ofthe interlocking matrix of set gypsum crystals, thereby impartingstrength to the gypsum structure in the product. Heat is required (e.g.,in a kiln) to drive off the remaining free (i.e., unreacted) water toyield a dry product.

A reduction in board weight is desired because of higher efficiencies ininstallation. For example, lifting demands are much less, which resultsin longer work days and less injuries. Lighter weight board is also more“green,” as it can result in reducing transportation expenditures andenergy consumption. To reduce the weight of the board, foaming agent canbe introduced into the slurry to form air voids in the final product.However, by their nature, foaming agents are generally unstable suchthat foam bubbles tend to break up easily, particularly in the presenceof cementitious material, thereby leading to waste and inefficiencies.

Furthermore, replacing mass with air in the gypsum board envelopereduces weight, but that loss of mass also results in less strength.Compensating for that loss in strength is a significant obstacle inweight reduction efforts in the art.

It will be appreciated that this background description has been createdby the inventors to aid the reader, and is not to be taken as areference to prior art nor as an indication that any of the indicatedproblems were themselves appreciated in the art. While the describedprinciples can, in some regards and embodiments, alleviate the problemsinherent in other systems, it will be appreciated that the scope of theprotected innovation is defined by the attached claims, and not by theability of any embodiments of the disclosure to solve any specificproblem noted herein.

BRIEF SUMMARY

In one aspect, the disclosure provides for “on-line” blending of foamingagent (soap) and foam modifier (soap modifier) to form a blended pre-mixfoam stream in a manner that allows for the relative weight amounts ofthe foaming agent and foam modifier to be adjusted. For example, thefoam has particular utility in the manufacture of foamed gypsum orcement board. The foam, which will result in voids in the dried product,is used so that the board is made lighter. The on-line blending allowsfor adjustments to the amounts of foaming agent(s) and foam modifierdirectly at the gypsum wallboard or cement board manufacturing facility.This flexibility is advantageous because it allows for tailoring theproperties of the board end product, e.g., with respect to the boardstructure, including the size and arrangement of voids in a board layercontaining voids formed from the foam.

Thus, a method of making a foamed cementitious board comprises, consistsof, or consists essentially of blending a first amount of a firstfoaming agent, a second amount of a second foaming agent, and a thirdamount of a fatty alcohol to form a blended stream, wherein the first,second, and third amounts are in a first weight ratio. In this step, thefirst or second foaming agent can be combined with the fatty alcoholfirst in a pre-stream and then added to the blended stream, e.g., in ablended stream conduit. The method also comprises controllably changingthe first, second, and/or third amounts to form a second weight ratio,which is different than the first weight ratio. The method furthercomprises inserting air into the blended stream to form foam; mixing atleast water, cementitious material, and the foam to form a slurry;disposing the slurry between a first cover sheet and a second coversheet to form a board precursor; cutting the board precursor into aboard; and drying the board.

In another aspect, a system for forming foam is provided. The systemcomprises, consists of, or consists essentially of a flow meteringsystem configured to introduce a first foaming agent, a second foamingagent, and fatty alcohol, irrespective of order, directly or indirectlyinto a foam generator. In some embodiments, the first foaming agent,second foaming agent, and fatty alcohol are combined, regardless oforder, prior to addition to the foam generator, e.g., in a blendedstream conduit. In some embodiments, the first foaming agent or secondfoaming agent is mixed with the fatty alcohol first, e.g., in apre-conduit prior to delivery to the blended stream conduit. Acontroller communicates with the flow metering system to selectivelychange the relative amounts of first foaming agent, second foamingagent, and fatty alcohol that are introduced directly or indirectly intothe foam generator (e.g., via the blended stream conduit). An air supplyconduit is provided to introduce air into the foam generator adapted toform foam.

In another aspect, a system for forming foam is provided. The systemcomprises, consists of or consists essentially of a flow metering systemcomprising at least one pump operatively associated with one or morevalve for controlling flow of a first foaming agent, a second foamingagent, and fatty alcohol into a blended stream conduit, irrespective oforder. A controller communicates with the low metering system toselectively change the relative amounts of first foaming agent, secondfoaming agent, and fatty alcohol that are introduced into the blendedstream conduit. A foam generator is in fluid communication with theblended stream conduit, and an air supply conduit introduces air intothe foam generator so that foam can be prepared.

In another aspect, a system for forming foam is provided. The systemcomprises, consists of, or consists essentially of a first pump which isused to introduce a first foaming agent from a first supply conduit viaa first valve into a blended stream conduit. A second pump is used tointroduce a second foaming agent from a second supply conduit via asecond valve into the blended stream conduit. A third pump is used tointroduce fatty alcohol from a third supply conduit via a third valveinto the blended stream conduit. A controller communicates with one ormore (e.g., all) of the first, second, and third valves and/or first,second and third pumps to selectively change the relative amounts offirst foaming agent, second foaming agent, and fatty alcohol that areintroduced into the blended stream conduit. A foam generator, containingagitation means, communicates with the blended stream conduit. An airsupply conduit introduces air into the foam generator. Thus, as thecontents of the blended stream are agitated and combined with air in thefoam generator, foam is formed. The foam can then be delivered to acementitious slurry, e.g., into a mixer where the cementitious slurry iscontinuously formed, for the preparation of board such as gypsumwallboard or cement board.

In another aspect, the disclosure provides a gypsum board comprising,consisting of, or consisting essentially of a set gypsum core disposedbetween two cover sheets. The set gypsum core comprises, consists of, orconsists essentially of a gypsum crystal matrix formed from at leastwater, stucco, and a foam. The foam is formed from a foaming agent, andfoam stabilizer comprising a fatty alcohol. Preferably, the foamingagent comprises, consists of, or consists essentially of at least onealkyl sulfate, at least one alkyl ether sulfate, or any combinationthereof in some embodiments, the foaming agent substantially excludes anolefin and/or alkyne foaming agent. Without wishing to be bound by anyparticular theory, the fatty alcohol is believed to interact with thefoaming agent to stabilize the foam and allow for better control of theair voids formed in the final product. In some embodiments, the foamstabilizer comprises the fatty alcohol but substantially excludes fattyacid alkyloamides and/or carboxylic acid taurides. In some embodiments,the board exhibits enhanced strength as compared with the same boardprepared without the fatty alcohol.

In another aspect, the disclosure provides a method of makingcementitious (e.g., gypsum or cement) board. Foam is typicallypregenerated. Thus, the method comprises, consists of, or consistsessentially of pregenerating a foam by inserting air into an aqueousmixture of foaming agent and a foam stabilizer comprising fatty alcohol.Preferably, the foaming agent comprises, consists of, or consistsessentially of at least one alkyl sulfate, at least one alkyl ethersulfate, or any combination thereof. Stable and unstable foaming agentscan be blended. In some embodiments, the foaming agent substantiallyexcludes an olefin and/or alkyne foaming agent. The foam is introduced(e.g., injected) into the slurry.

The method includes mixing at least water, stucco, and the foam to forma cementitious slurry; disposing the slurry between a first cover sheetand a second cover sheet to form a board precursor; cutting, the boardprecursor into a board; and drying the board. In preferred embodiments,the fatty alcohol can be combined with the foaming agent in a pre-mixand the pre-mix added to stucco, water, and other additives, as desired,e.g., in a mixer. While not wishing to be bound by theory, the fattyalcohol is believed to be generally solubilized in the aqueous foamingagent. In some embodiments, the foam stabilizer comprises the fattyalcohol but substantially excludes a glycol and/or amide compound.

In another aspect, the disclosure provides a method of forming a foamedgypsum slurry. The method comprises, consists of, or consistsessentially of combining a foaming agent with a fatty alcohol to form anaqueous soap mixture; generating a foam from the aqueous soap mixture;and adding the foam to a gypsum slurry comprising stucco and water toform the foamed gypsum slurry. Without wishing to be bound by anyparticular theory, as the foam is entrained in the gypsum slurry, foambubbles are formed with a shell surrounding the bubbles interfacing theslurry. It is further believed that the presence of fatty alcoholdesirably stabilizes the shell at the interface.

In another aspect, the disclosure provides a slurry comprising,consisting, or consisting essentially of water, stucco, foaming agent,and a fatty alcohol, wherein, when the slurry is cast and dried asboard, the board has increased strength compared to the same boardformed without the fatty alcohol.

In another aspect, the disclosure provides a method of stabilizing afoamed structure in a cementitious slurry, e.g., used in the preparationof cementitious (e.g., gypsum or cement) board. In the method, fattyalcohol can be combined with foaming agent. In some embodiments, thefoaming agent is mixed with the fatty alcohol to form an aqueous soapmixture. A foam is generated from the aqueous soap mixture. The foam isadded to a gypsum or cement slurry comprising cementitious material(e.g., stucco or cement) and water to form a foamed cementitious slurry.Without wishing to be bound by any particular theory, it is believedthat, as the foam is entrained in the cementitious slurry, foam bubblesare formed with a shell surrounding the bubbles interfacing the slurry.It is further believed that the presence of fatty alcohol desirablystabilizes the shell at the interface.

To make the board, the foamed cementitious slurry is applied in abonding relation to a top (or face) cover sheet to form a foamedcementitious core slurry having first and second major surfaces. Thefirst major surface of the foamed cementitious core slurry faces the topcover sheet. A bottom (or back) cover sheet is applied in bondingrelation to the second major surface of the foamed cementitious coreslurry to form a wet assembly of board precursor. If desired, a skimcoat can be applied between the core and either or both of the coversheets. The board precursor is cut and dried to form the board product.

In another aspect, the disclosure provides cement board formed from acore mix of water arid a cement material (e.g., Portland cement, aluminacement, magnesia cement, etc., and blends of such materials). A foamingagent and fatty alcohol is also included in the mix. Optionally,light-weight aggregate (e.g., expanded clay, expanded slag, expandedshale, perlite, expanded glass beads, polystyrene beads, and the like)can be included in the mix in some embodiments. The cement boardcomprises a cement core disposed between two cover sheets. The cementcore can be formed from at least water, cement, foaming agent, and afatty alcohol.

In another aspect, the disclosure provides a method of forming a foamedcement slurry. The method comprises, consists of or consists essentiallyof combining a foaming agent with a fatty alcohol to form an aqueoussoap mixture; generating a foam from the aqueous soap mixture; andadding the foam to a cement slurry comprising cement (e.g., Portlandcement, alumina cement, magnesia cement, etc., or combinations thereof)and water to form the foamed cement slurry. As the foam is entrained inthe cement slurry, foam bubbles are formed with a shell surrounding thebubbles interfacing the slurry. Without wishing to be bound by anyparticular theory, the presence of fatty alcohol desirably stabilizesthe shell at the interface.

In another aspect, the disclosure provides a stony comprising,consisting, or consisting essentially of water, cement, foaming agent,and a fatty alcohol, wherein, when the slurry is formed and dried asboard, the board has increased strength compared to the same boardformed without the fatty alcohol.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bar graph of foam height (mm) (Y-Axis) versus foaming agentsolutions absent fatty alcohol (X-axis) both with and withoutpolycarboxylate ether, as described in Example 1 herein.

FIG. 2 is a bar graph of foam height (mm) (Y-axis) versus foaming agentsolutions containing Foaming Agent 1B (X-axis), as described in Example1 herein.

FIG. 3 is a bar graph of foam height (mm) (Y-axis) versus foaming agentsolutions containing Foaming Agent 1C (X-axis), as described in Example1 herein.

FIG. 4 is a graph of foam height (mm) (Y-axis) versus time (X-axis) offoaming agent solutions containing Foaming Agent 1B, as described inExample 1 herein.

FIG. 5 is a graph of foam height (mm) (Y-axis) versus time (X-axis) offoaming agent solutions containing Foaming Agent 1C, as described inExample 1 herein.

FIGS. 6A-6C are optical micrograph images at 20 times magnification ofthe cross-section of a control wallboard 2A prepared without any fattyalcohol, as described in Example 2 herein.

FIGS. 7A-7C are optical micrograph images at 20 times magnification ofthe cross-section of wallboard 2B prepared with a foaming agent blendwith 1% of dodecanol, as described in Example 2 herein

FIGS. 8A-8C are optical micrograph images at 20 times magnification ofthe cross-section of wallboard 2C prepared with a foaming agent blendwith 1% of decanol, as described in Example 2 herein.

FIGS. 9A-9C are optical micrograph images at 20 times magnification ofthe cross-section of wallboard 2D prepared with a foaming agent blendwith 1% of octanol, as described in Example 2 herein.

FIG. 10 is a bar graph of volumetric distribution (%) (Y-axis) versusvoid size in control wallboard 2A, as described in Example 2 herein,

FIG. 11 is a bar graph of volumetric distribution (%) of voids (Y-axis)versus void size (microns) (X-axis) in wallboard 2B prepared withfoaming agent modified with 1% dodecanol, as described in Example 2herein.

FIG. 12 is a bar graph of volumetric distribution (%) (Y-axis) versusvoid size (microns) (X-axis) in wallboard 2C prepared with foaming agentmodified with 1% decanol, described in Example 2 herein.

FIG. 13 is a bar graph of volumetric distribution (IN (Y-axis) versusvoid size (microns) (X-axis) in wallboard 2D prepared with foaming agentmodified with 1% octanol, as described in Example 2 herein.

FIG. 14 is a schematic diagram of an embodiment of a system forpreparing a foam that includes stable and unstable soaps (foamingagents) and soap (foam) modifier such that the foam is useful, forexample, for insertion into a gypsum or cement slurry during themanufacture of board.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the disclosure provide a foam modifier useful forcementitious slurries (e.g., gypsum or cement slurries), and for relatedproducts and methods. The foam modifier is a fatty alcohol, which, whilenot wishing to be bound by any particular theory, is believed to act tohelp stabilize foam. Gypsum and cement slurries can be complex systemswith varying types and amounts of materials. The ingredients within theslurry contribute stress to foam, which can cause foam bubbles to breakup, resulting in reduced control of air void size distribution.Surprisingly and unexpectedly, the inventors have found that inclusionof the fatty alcohol with the foaming agent, e.g., in a pre-mix toprepare the foam, can result in an improvement in the stability of thefoam, thereby allowing better control of foam (air) void size anddistribution. By forming such a robust foaming system, in someembodiments the controlled core structure can result in improved boardstrength, as seen in, e.g., improved nail pull resistance (sometimesreferred to simply as “nail pull”), core hardness, etc. In someembodiments, the board has increased strength compared to the same boardformed without the fatty alcohol. The air void size distribution of thecore structure can be tailored as desired, e.g., to have an average voiddiameter that can be higher or lower, e.g., comprising larger air voidsor smaller air voids, as can be predetermined.

The fatty alcohol can be used with any suitable foaming agentcomposition useful for generating foam in gypsum slurries. Suitablefoaming agents are selected to result in air voids in the final productsuch that the weight of the board core can be reduced. In someembodiments, the foaming agent comprises a stable soap, an unstablesoap, or a combination of stable and unstable soaps. In someembodiments, one component of the foaming agent is a stable soap, andthe other component is a combination of a stable soap and unstable soap.In some embodiments, the foaming agent comprises an alkyl sulfitesurfactant.

Many commercially known foaming agents are available and can be used inaccordance with embodiments of the disclosure, such as the HYONIC line(e.g., 25AS) of soap products from GEO Specialty Chemicals, Ambler, Pa.Other commercially available soaps include the Polystep B25, from StepanCompany, Northfield, Ill. The foaming agents described herein can beused alone or in combination with other foaming agents.

Some types of unstable soaps, in accordance with embodiments of thedisclosure, are alkyl sulfate surfactants with varying chain length andvarying cations. Suitable chain lengths, can be, for example, C₈-C₁₂,e.g., C₈-C₁₀, car C₁₀-C₁₂. Suitable cations include, for example,sodium, turimonium, magnesium, or potassium. Examples of unstable soapsinclude, for example, sodium dodecyl sulfate, magnesium dodecyl sulfate,sodium decyl sulfate, ammonium dodecyl sulfate, potassium dodecylsulfate, potassium decyl sulfate, sodium octyl sulfate, magnesium decylsulfate, ammonium decyl sulfate, blends thereof, and any combinationthereof.

Some types of stable soaps, in accordance with embodiments of thedisclosure, are alkoxylated (e.g., ethoxylated) alkyl sulfatesurfactants with varying (generally longer) chain length and varyingcations. Suitable chain lengths, can be, for example, C₁₀-C₁₄, e.g.,C₁₂-C₁₄, or C₁₀-C₁₂. Suitable cations include, for example, sodium,ammonium, magnesium, or potassium. Examples of stable soaps include, forexample, sodium laureth sulfate, potassium laureth sulfate, magnesiumlaureth sulfate, ammonium laureth sulfate, blends thereof, and anycombination thereof. In some embodiments, an combination of stable andunstable soaps from these lists can be used.

Examples of combinations of foaming agents and their addition inpreparation of foamed gypsum products are disclosed in U.S. Pat. No.5,643,510, herein incorporated by reference. For example, a firstfoaming agent which forms a stable foam and a second foaming agent whichforms an unstable foam can be combined, in some embodiments, the firstfoaming agent is a soap with an alkyl chain length of 8-12 carbon atomsand an alkoxy (e.g., ethoxy) group chain length of 1-4 units. The secondfoaming agent is optionally an unalkoxylated (e.g., unethoxylated) soapwith an alkyl chain length of 6-20 carbon atoms, e.g., 6-18 carbon atomsor 6-16 carbon atoms. Regulating the respective amounts of these twosoaps allows for control of the board foam structure until about 100%stable soap or about 100% unstable soap is reached.

In some embodiments, the foaming agent is in the form of an alkylsulfate and/or alkyl ether sulfate. Such foaming agents are preferredover olefins such as olefin sulfates because the olefins contain doublebonds, generally at the front of the molecule thereby making themundesirably more reactive, even when made to be a soap. Thus,preferably, the foaming agent comprises alkyl sulfate and/or alkyl ethersulfate but is essentially free of an olefin (e.g., olefin sulfate)and/or alkyne. Essentially free of olefin or alkyne means that thefoaming agent contains either (i) 0 wt. % based on the weight of stucco,or no olefin and/or alkyne, or (ii) an ineffective or (iii) animmaterial amount of olefin and/or alkyne. An example of an ineffectiveamount is an amount below the threshold amount to achieve the intendedpurpose of using olefin and/or alkyne foaming agent, as one of ordinaryskill in the art will appreciate. An immaterial amount may be, e.g.,below about 0.001 wt. %, such as below about 0.005 wt. %, below about0.001 wt. %, below about 0.0001 wt. %, etc., based on the weight ofstucco, as one of ordinary skill in the art will appreciate.

The foaming agent is included in the gypsum slurry in any suitableamount. For example, in some embodiments, it is included in an amount offrom about 0.01% to about 0.25% by weight of the stucco, e.g, from about0.01% to about 0.1% by weight of the stucco, from about 0.01% to about0.03% by weight of the stucco, or from about 0.07% to about 0.1% byweight of the stucco.

The fatty alcohol can be any suitable aliphatic fatty alcohol. it willbe understood that, as defined herein throughout, “aliphatic” refers toalkyl, alkenyl, or alkynl, and can be substituted or unsubstituted,branched or unbranched, and saturated or unsaturated, and in relation tosome embodiments, is denoted by the carbon chains set forth herein,e.g., C_(x)-C_(y), where x and y are integers. The term aliphatic thusalso refers to chains with heteroatom substitution that preserves thehydrophobicity of the group. The fatty alcohol can be a single compound,or can be a combination of two or more compounds.

In some embodiments, the fatty alcohol is a C₆-C₂₀ fatty alcohol, suchas a C₁₀-C₂₀ fatty alcohol or C₆-C₁₆ fatty alcohol (e.g., C₆-C₁₄,C₆-C₁₂, C₆-C₁₀, C₆-C₈, C₈-C₁₆, C₈-C₁₄, C₈-C₈-C₁₂, C₈-C₁₀, C₁₀-C₁₆,C₁₀-C₁₄, C₁₀-C₁₂, C₁₂-C₁₆, C₁₂-C₁₄, or C₁₄-C₁₆ aliphatic fatty alcohol,etc.). Examples include octanol, decanol, dodecanol, etc. or anycombination thereof.

The C₁₀-C₂₀ fatty alcohol comprises a linear or branched C₆-C₂₀ carbonchain and at least one hydroxyl group. The hydroxyl group can beattached at any suitable position on the carbon chain but is preferablyat or near either terminal carbon. In certain embodiments, the hydroxylgroup can be attached at the α-, β-, or γ-position of the carbon chain,for example, the C₆-C₂₀ fatty alcohol can comprise the followingstructural subunits:

Thus, examples of a desired fatty alcohol in accordance with someembodiments are 1-dodecanol, 1-undecanol, 1-decanol, 1-nonanol,1-octanol, or any combination thereof.

In some embodiments, a foam stabilizing agent comprises the fattyalcohol and is essentially free of fatty acid alkyloamides or carboxylicacid taurides. In some embodiments, the foam stabilizing agent isessentially free of a glycol, although glycols can be included in someembodiments, e.g., to allow for higher surfactant content. Essentiallyfree of any of the aforementioned ingredients means that the foamstabilizer contains either (i) 0 wt. % based on the weight of any ofthese ingredients, or (ii) an ineffective or (iii) an immaterial amountof any of these ingredients. An example of an ineffective amount is anamount below the threshold amount to achieve the intended purpose ofusing any of these ingredients, as one of ordinary skill in the art willappreciate. An immaterial amount may be, e.g., below about 0.0001 wt. %,such as below about 0.00005 wt%, below about 0.00001 wt. %, below about0.000001 wt. %, etc., based on the weight of stucco, as one of ordinaryskill in the art will appreciate.

The fatty alcohol can be present in the gypsum slurry in any suitableamount. In some embodiments, the fatty alcohol is present in an amountof from about 0.0001% to about 0.03% by weight of the stucco, e.g., fromabout 0.0001% to about 0.001% by weight of the stucco, from about0.0002% to about 0.0075% by weight of the stucco, from about 0.0001% toabout 0.003% by weight of the stucco, or from about 0.0005% to about0.001% by weight of the stucco.

In preferred embodiments, to enhance efficiency, the foaming agent, foamwater, and fatty alcohol are combined prior to addition to the gypsumslurry. Preparation in this manner enables the fatty alcohol to actdirectly with the foam to provide the desired stabilization effect,rather than be diluted in the gypsum slurry and compete with othercomponents of the slurry for access to foam bubbles.

The fatty alcohol can be added to foaming agent and typically dissolved.Since fatty alcohols are generally water insoluble, they are added tothe soap and solubilized first prior to foam generation in someembodiments. The fatty alcohol can be dissolved in stable or unstablefoaming agents in accordance with embodiments of the disclosure. In someembodiments, a first foaming agent, with dissolved fatty alcohol, isthen blended with another foaming agent (e.g., a stable foaming agentwith a dissolved fatty alcohol blended with an unstable foaming agent,or an unstable foaming agent with a dissolved fatty alcohol blended witha stable foaming agent).

Any effective weight proportion between the surfactants (foaming agents)and fatty alcohols can be used in the final foaming agent-fatty alcoholblend, prior to addition to the gypsum slurry. For example, the foamingagent can be present relative to fatty alcohol in a weight ratio of fromabout 5000:1 to about 5:1, e.g., from about 5000:1 to about 1000:1, fromabout 500:1 to about 100:1, or from about 500:1 to about 10:1. Toillustrate, in one embodiment, a typical final foaming agent-fattyalcohol blend has 30% surfactants and 1% fatty alcohols by weight, withthe remainder of the mixture composed of water.

The foaming agent and fatty alcohol can be blended in a container bymixing (stirring, agitation). The additional foaming agent can be addedby injection. In accordance with preferred embodiments, the foam ispregenerated and prestabilized before it meets the cementitious slurry.While not wishing to be bound by theory, it is believed that a thin filmof surfactant is formed which is modified with fatty alcohol beforemixing it with the cementitious slurry. Pregeneration of the foaminvolves high shear mixing of pressurized air with soap solution. Thispregeneration of foaming agent is preferred as it leads to a foam, whichis in contrast with systems that merely entrain some air during mixingwithout making foams. These air entrainment systems merely add bubblesby simply blending the slurry containing some soap. A foam can bedistinguished from such mixed bubble systems because pregenerated foambubble size is more uniform and can be controlled.

After the foaming agent composition blend with fatty alcohol iscombined, the foam is generated and then added (e.g., injected) to theslurry. Methods and apparatus for generating foam are well known. See,e.g., U.S. Pat. Nos. 4,518,652; 2,080,009; and 2,017,022. The foam canbe pregenerated from the aqueous foaming agent-fatty alcohol mixture.For example, the final composition of the foaming agent and fattyalcohol combination can be directed via dosage adjustments to the foamgenerator equipment. One method of making the foam is using a foamgenerator that mixes the soap solution with air. Any method of mixingcan be used to combine the soap with air that causes bubbles to beformed, including agitation, turbulent flow or mixing. For example, thefoam generator equipment can include compressed air and surfactantsolution mixed in order to generate the foam. The amount of water andair are controlled to generate foam of a particular density. Adjustmentof the foam volume is used to control the overall dry product weight.

If desired, a mixture of foaming agents can be pre-blended “off-line”,i.e., separate from the process of preparing the foamed gypsum product.However, it is preferable to blend the first and second foaming agentsconcurrently and continuously, as an integral “on-line” part of themixing process. This can be accomplished, for example, by pumpingseparate streams of the different foaming agents and bringing thestreams together at, or just prior to, a foam generator that is employedto generate the stream of aqueous foam which is then inserted into andmixed with the calcined gypsum slurry. By blending in this manner, theratio of the first and second foaming agents in the blend can be simplyand efficiently adjusted (for example, by changing the flow rate of oneor both of the separate streams) to achieve the desired voidcharacteristics in the foamed set gypsum product. Such adjustment willbe made in response to an examination of the final product to determinewhether such adjustment is needed. Further description of such “on-line”blending and adjusting can be found in U.S. Pat. Nos. 5,643,510 and5,683,635, incorporated by reference.

On-line addition of the foam is advantageous in some embodiments becauseit allows for one or more soaps to be combined with the foam modifier asdescribed herein in a pre-mix, which is then inserted into the gypsumslurry, e.g., in the main mixer for the gypsum slurry. Addition of thesoap and soap (foam) modifier in this mariner allows for flexibility inthe system as the relative weights of each component can be adjusted,e.g., with the aid of a process controller as known in the art. Thus,the individual amounts of one or more soaps and the soap modifier can becontrolled with better precision and allows for flexibility duringmanufacture that is not available from a combined source of soap(foaming agent) and soap modifier (foam modifier) prepared off-site withpredetermined relative amounts of the respective components (i.e., soapand soap modifier).

FIG. 14 is schematic flow diagram that illustrates an embodiment of afoam generating system 10 where the foaming agent (soap) and foammodifier (soap modifier) are combined in a pre-mix that can be adjustedwith respect to the amounts of each component, in particular, anunstable soap 12, a soap modifier 14, and a stable soap 16, as describedherein, are introduced through individual conduits in any order into ablended stream conduit 18. Foam water 20 can also be added into theblended stream conduit 18 in order to dilute the surfactant solution.Foam air 24 is introduced to achieve the desired target foam density(e.g., from about 2 lb/ft³ to about 8 lb/ft³, from about 3 lb/ft³ toabout 7 lb/ft³, or from about 4 lb/ft³ to about 6 lb/ft³, etc.) as maybe suitable for foam generation.

The contents of the blended stream conduit 18 are inserted into a foamgenerator 22. Clean, dry air 24 is also inserted into foam generator 22and is used to form the foam 26. The foam generator 22 generallycontains a rotor and stator, as known in the art. The foam generatormixes the air, water, and foaming agents under pressure using a shearingaction between the rotor and stator to produce the foam. The air can besupplied through a conduit with precise control of air pressure (e.g.,from about 40 psi to about 100 psi, or from about 40 psi to about 80psi) and flow rate (e.g., from about 20 ft³/min to about 60 ft³/min, orfrom about 30 ft³/min to about 50 ft³/min). The foam 26 can then bedelivered to a mixer for forming a cementitious slurry which is used toform board such as a gypsum board or cement board, as known in the art.

Advantageously, the system 10 allows for on-line adjustment of thecomponents used in making the foam, particularly, the unstable soap 12,soap modifier 14, and stable soap 16. The unstable soap 12, soapmodifier 14 and stable soap 16 can each be preformed and deliveredthrough individual conduits to the blended stream conduit 18, ifdesired, the unstable soap 12 and the soap modifier 14 can be combinedfirst in a pre-conduit and/or, similarly, the stable soap 16 and thesoap modifier 14 can be combined first in a pre-conduit. Insertion ofthe components 12, 14, and 16 can be assisted by a flow metering systemas described below.

The system 10 allows for on-the-fly adjustment of the relative amountsof each component 12, 14, and 16, even as the foam generating system iscontinuously forming foam and the cementitious slurry mixer iscontinuously forming board. To illustrate, the components 12, 14, and 16can be present in a first weight ratio but an operator (e.g., a boardline operator) can adjust the amounts of one or more of components 12,14 and 16 so as to form a second weight ratio, all on the fly while thefoam and, in turn, the board, are continuously prepared. For example,the operator may wish to change the relative amounts of components 12,14 and 16 in order to achieve a target air void structure in the hoardlayer and to control the void size distribution as known in the art.This may be in response to a visual inspection of a sample of wet slurryand/or a cross-section of board sampled downstream (for example, in wetform, e.g. at the knife, or after drying), and particularly byinspection of a gypsum layer containing voids resulting from the foam.

The flow metering system can include one or more pumps and one or morevalves in some embodiments. For example, one or more pumps (e,g.,progressive cavity or positive displacement pumps) can be used tofacilitate injection of the particular foaming agent or foam modifiercomponent into the blended stream conduit 18. In some embodiments, thepumps are in the form of high precision pumps and contain a flow-meterin order to quantify the material flow. Valves or other flow regulatorare used to regulate the amount of each component 12, 14, and 16injected into the blended stream conduit 18. Any suitable valves can beutilized as known in the art, such as solenoid or pulsing valves (e.g.,valves that pulse with modulation).

In various embodiments, the flow metering system can be configured sothat one, two, or three pumps are operatively associated with valves forthe first foaming agent, second foaming agent, and foam modifier. Forexample, in some embodiments, three pumps are employed, one for each ofthe first foaming agent, the second foaming agent, and the foammodifier. In some embodiments, such as where one of the two foamingagents is combined with the foam modifier first prior to addition to theother foaming agent, two pumps can be used, e.g., where one pump is usedfor two ingredients that are combined first, and the other pump is usedfor the third ingredient. In other embodiments, a single pump is usedand is adapted for injection of the first foaming agent, the secondfoaming agent, and the foam modifier.

A process controller can be utilized to operate the flow metering systemfor on-line adjustments in some embodiments. The process controller cancommunicate with the pumps and/or valves of the flow metering system toadjust the amounts of first foaming agent, second foaming agent, andfoam modifier. Hardware and operating systems for operating the flowmetering system using pumps and valves are well known. Briefly, thecontroller can be in the form of a chip or electronic control unit andcan be associated with a computer module provided with memory in someembodiments. The valves and pumps can have automated settings for one ormore desired features, e.g., on/off, rate of pulsing, actuation rate,flow rate, flow pressure, etc., which can be installed, for example, inthe memory of the module. The controller can receive instructions, e.g.,from a human operator, and responsively send a control output signal tothe valves and/or pumps, e.g., through the settings thereof. This allowsfor on-line adjustments of the amounts of one or more of components 12,14 and 16 as the pumps and/or valves can adjust one or more of the flowrate, flow pressure, rate of pulsing, actuation rate, etc., as will beappreciated by one of ordinary skill in the art.

The slurry and pregenerated foam can be combined to make a foamed gypsumcomposition. One method of combining the gypsum slurry and thepregenerated foam is by pressurizing the foam and forcing it into theslurry. At least one embodiment uses a foam ring to distribute the foam.The foam ring is a shaped apparatus that allows the slurry to flowthrough it. It includes one or more jets or slots for discharge of thepressurized foam into the slurry as the slurry passes the ring. Use of afoam ring is disclosed in U.S. Pat. No. 6,494,609, herein incorporatedby reference. Another method of combining the foam and the slurry is byaddition of the foam directly to the mixer. In one embodiment, a foamring or other foam injecting apparatus is oriented to inject foam intothe discharge conduit of the mixer. This process is described incommonly-assigned U.S. Pat. No. 5,683,635, incorporated by reference.Regardless of the way that the foam is generated or introduced into theslurry, an important feature of the present method is that the fattyalcohol is combined or added at some point in the foam production orgeneration prior to its introduction into the slurry. The gypsumcomposition is shaped to form a gypsum core.

The gypsum crystal matrix of the set gypsum core formed with the fattyalcohol and foaming agent regime of the disclosure can be tailored tohave any desired pore size distribution. Soap usage differs from productto product depending on the desired void size and distribution, as willbe appreciated by one of ordinary skill in the art. Techniques foradjusting void sizes as desired are well known and will be understood byone of ordinary skill in the art. See, e.g., U.S. Pat. No. 5,643,510 andUS 2007/0048490. For example, void size distribution of the foamedgypsum core can be finely controlled by adjusting the concentration ofthe soaps in the aqueous soap mixture. After a foamed gypsum core has,been prepared, inspection of the interior of the gypsum core reveals thevoid structure. Changes in the void size distribution are produced byvarying the soap concentration from the initial or previousconcentration. If the interior has too large a fraction of small voids,the soap concentration in the aqueous soap mixture can be reduced if toomany very large, oblong or irregularly shaped voids are found, the soapconcentration can be increased. Although the optimum void sizedistribution may vary by product, location or raw materials used, thisprocess technique is useful to move towards the desired void sizedistribution, regardless of how it is defined. The desirable void sizedistribution in many embodiments is one that produces a high strengthcore for the gypsum formulation being used.

For example, in some embodiments, the set gypsum core comprises airvoids having an average air void diameter of relatively large air voids,such as an average air void diameter of at least about 100 microns indiameter, an average air void diameter of at least about 150 microns indiameter, an average air void diameter of at least about 200 microns indiameter, an average air void diameter of at least about 250 microns indiameter, an average air void diameter of at least about 300 microns indiameter, or an average air void diameter of at least about 350 micronsin diameter, etc.

In some embodiments, the set gypsum core comprises air voids having anaverage air void diameter of relatively small air voids, such as anaverage air void diameter of less than about 100 microns in diameter, anaverage air void diameter of less than about 90 microns in diameter, anaverage air void diameter of less than about 80 microns in diameter, anair average void diameter of less than about 70 microns in diameter, anaverage air void diameter of less than about 60 microns in diameter, oran average air void diameter of less than about 50 microns in diameter,etc.

In some embodiments, the gypsum crystal matrix has a pore sizedistribution comprising voids, wherein the air void size having greatestfrequency is a diameter of about 100 microns or less, about 80 micronsor less, about 70 microns or less, or about 50 microns or less. In otherembodiments, the gypsum crystal matrix has a pore size distributioncomprising air voids wherein the air void size having greatest frequencyis a diameter of at least about 100 microns, such as a diameter of atleast about 150 microns, at least about 200 microns, etc.

In some embodiments, to enhance strength, the set gypsum core includes asignificant void volume contributed by large voids, i.e., having adiameter of at least about 100 microns. For example, in someembodiments, at least about 20% of the total void volume of the setgypsum core is contributed by voids having a diameter of at least about100 microns, such as at least about 30% of the total void volume of theset gypsum core, at least about 40% of the total void volume of the setgypsum core, at least about 50% of the total void volume of the setgypsum core, at least about 60% of the total void volume of the setgypsum core, at least about 70% of the total void volume of the setgypsum core, at least about 80% of the total void volume of the setgypsum core, or at least about 90% of the total void volume of the setgypsum core. To enhance weight reduction while maintaining strength, insome embodiments, smaller generally discrete air voids at highfrequency, i.e., having a diameter of less than about 100 microns and/orhaving a diameter of less than about 50 microns, can be disposed betweenthe large voids. In some embodiments, the air void size having greatestfrequency is a diameter of about 100 microns or less, about 80 micronsor less, about 70 microns or less, or about 50 microns or less, while atthe same time the void volume contribution by air voids having adiameter of at least about 100 microns can be any according to any ofthe volume percentages stated above. In some embodiments, thedistribution of air voids is relatively narrow, which can becharacterized by image analysis of micrographs or other images of thecore structure.

As used herein, the term average air void size (also referred to as theaverage air void diameter) is calculated from the largest diameter ofindividual air voids in the core. The largest diameter is the same asthe Feret diameter. The largest diameter of each air void can beobtained from an image of a sample. Images can be taken using anysuitable technique, such as scanning electron microscopy (SEM), whichprovides two-dimensional images. A large number of pore sizes of airvoids can be measured in an SEM image, such that the randomness of thecross sections (pores) of the voids can provide the average diameter.Taking measurements of voids in multiple images randomly situatedthroughout the core of a sample can improve this calculation.Additionally, building a three-dimensional stereological model of thecore based on several two-dimensional SEM images can also improve thecalculation of the average void size. Another technique is X-rayCT-scanning analysis (XMT), which provides a three-dimensional image.Another technique is optical microscopy, where light contrasting can beused to assist in determining, e.g., the depth of voids. The voids canbe measured either manually or by using image analysis software, e.g.,ImageJ, developed by NIH. One of ordinary skill in the art willappreciate that manual determination of void sizes and distribution fromthe images can be determined by visual observation of dimensions of eachvoid. The sample can be obtained by sectioning a gypsum board.

Evaporative water voids, generally having voids of about 5 μm or less indiameter, also contribute voids along with the aforementioned air (foam)voids. In some embodiments, the volume ratio of voids with a pore sizegreater than about 5 microns to the voids with a pore size of about 5microns or less, is from about 0.5:1 to about 9:1, such as, for example,from about 0.7:1 to about 9:1, from about 0.8:1 to about 9:1, from about1.4:1 to about 9:1, from about 1.8:1 to about 9:1, from about 2.3:1 toabout 9:1, from about 0.7:1 to about 6:1, from about 1.4:1 to about 6:1,from about 1.8:1 to about 6:1, from about 0.7:1 to about 4:1, from about1.4:1 to about 4:1, from about 1.8:1 to about 4:1, from about 0.5:1 toabout 2.3:1, from about 0.7:1 to about 2.3:1, from about 0.8:1 to about2.3:1, from about 1.4:1 to about 2.3:1, from about 1.8:1 to about 2.3:1,etc.

While not wishing to be bound by any particular theory, the fattyalcohol is believed to enhance stability of foam bubbles formed from thefoaming agent when the foam is introduced into the gypsum slurry(sometimes referred to as a “stucco slurry”). The foam bubbles arefurther believed to form an outer shell at an interface with thesurrounding gypsum slurry. The fatty alcohol is believed to strengthenand stabilize the shell at the interface to thereby provide improvedcontrol over void size and distribution. In addition, because of theimproved stability, less foam bubbles break up, and thus less foamingagent is needed in some embodiments to achieve the same desired boardweight reduction as compared to the same board prepared without thefatty alcohol. It is further believed that the foaming agent formsmicelles. In this regard, foaming agents are generally surfactants witha hydrophobic tails and hydrophilic heads. The fatty alcohols can beincorporated into the surfactant micelles such that the hydrophobicregions from the surfactants and from the fatty alcohols are adjacent toeach other to protect the foam bubbles by hydrophobic interactionsbetween the hydrophobic regions.

The gypsum slurry includes water and stucco. Any suitable type of stuccocan be used in the gypsum slurry, including calcium sulfate alphahemihydrate, calcium sulfate beta hemihydrate, calcium sulfateanhydrate. The stucco can be fibrous or non-fibrous. Embodiments of thedisclosure can accommodate any suitable water-to-stucco ratio (WSR). Insome embodiments, the WSR is from about 0.3 to about 1.5, such as, forexample, from about 0.3 to about 1.3, from about 0.3 to about 1.2, fromabout 0.3 to about 1, from about 0.3 to about 0.8. from about 0.5 toabout 1.5, from about 0.5 to about 1.3, from about 0.5 to about 1.2,from about 0.5 to about 1, from about 0.5 to about 0.8, from about 0.7to about 1.5, from about 0.7 to about 1.3, from about 0.7 to about 1.2,from about 0.7 to about 1, from about 0.8 to about 1.5, from about 0.8to about 1.3, from about 0.8 to about 1.2, from about 0.8 to about 1,from about 0.9 to about 1.5, from about 0.9 to about 1.3, from about 0.9to about 1.2. from about 1 to about 1.5, from about 1 to about 1.4, fromabout 1 to about 1.2, etc.

Surprisingly and unexpectedly, the improved stability of foam voids, andrelated resultant benefits described herein, can be achieved even in thepresence of various gypsum slurry additives and amounts used in formingthe board core. As such, the improved modified pre-foam mix comprisingfoaming agent and fatty alcohol in accordance with embodiments of thedisclosure can be used in the preparation of various types of gypsumproducts including ultra lightweight board, mold and water-resistantboard, and fire-rated products.

The gypsum slurry can include accelerators or retarders as known in theart to adjust the rate of setting. Accelerator can be in various forms(e.g., wet gypsum accelerator, heat resistant accelerator, and climatestabilized accelerator). See, e.g., U.S. Pat. Nos. 3,573,947 and6,409,825. In some embodiments where accelerator and/or retarder areincluded, the accelerator and/or retarder each can be in the stuccoslurry for forming the board core in an amount on a solid basis of, suchas, from about 0% to about 10% by weight of the stucco (e.g., about 0.1%to about 10%), such as, for example, from about 0% to about 5% by weightof the stucco (e.g., about 0.1 to about 5%).

Other additives can be included in the gypsum slurry to provide desiredproperties, including green strength, sag resistance, water resistance,mold resistance, fire rating, thermal properties, board strength, etc.Examples of suitable additives include, for example, strength additivessuch as stare, dispersant, polyphosphate, high expansion particulate,heat sink additive, fibers, siloxane, magnesium oxide, etc., or anycombination thereof. The use of the singular term additive herein isused for convenience but will be understood to encompass the plural,i.e., more than one additive in combination, as one of ordinary skill inthe art will readily appreciate.

In some embodiments, the gypsum slurry includes a starch that iseffective to increase the strength of the gypsum board relative to thestrength of the board without the starch (e.g., via increased nail pullresistance). Any suitable strength enhancing starch can be used,including hydroxyalkylated starches such as hydroxyethylated orhydroxypropylated starch, or a combination thereof, or pregelatinizedstarches, which are generally preferred over acid-modifying migratingstarches which generally provide paper-core bond enhancement but notcore strength enhancement. Any suitable pregelatinized starch can beincluded in the enhancing additive, as described in US 2014/0113124 A1and US 2015/0010767-A1, including methods of preparation thereof anddesired viscosity ranges described therein.

If included, the pregelatinized starch can exhibit any suitableviscosity. In some embodiments, the pregelatinized starch is a mid-rangeviscosity starch as measured according to the VMA method as known in theart and as set forth in US 2014/0113124 A1, which VMA method is herebyincorporated by reference. Desirable pregelatinized starches inaccordance with some embodiments can have a mid-range viscosity, e.g.,according to the VMA method when measured in a 15 wt. % solution ofstarch in water, of from about 20 centipoise to about 700 centipoise,e,g., from about from about 20 centipoise to about 600 centipoise, fromabout 20 centipoise to about 500 centipoise, from about 20 centipoise toabout 400 centipoise, from about 20 centipoise to about 300 centipoise,from about 20 centipoise to about 200 centipoise, from about 20centipoise to about 100 centipoise, from about 30 centipoise to about700 centipoise, from about 30 centipoise to about 600 centipoise, fromabout 30 centipoise to about 500 centipoise, from about 30 centipoise toabout 400 centipoise, from about 30 centipoise to about 300 centipoise,from about 30 centipoise to about 200 centipoise, from about 30centipoise to about 100 centipoise, from about 50 centipoise to about700 centipoise, from about 50 centipoise to about 600 centipoise, fromabout 50 centipoise to about 500 centipoise, from about 50 centipoise toabout 400 centipoise, from about 50 centipoise to about 300 centipoise,from about 50 centipoise to about 200 centipoise, from about 50centipoise to about 100 centipoise, from about 70 centipoise to about700 centipoise, from about 70 centipoise to about 600 centipoise, fromabout 70 centipoise to about 500 centipoise, from about 70 centipoise toabout 400 centipoise, from about 70 centipoise to about 300 centipoise,from about 70 centipoise to about 200 centipoise, from about 70centipoise to about 100 centipoise, from about 100 centipoise to about700 centipoise, from about 100 centipoise to about 600 centipoise, fromabout 100 centipoise to about 500 centipoise, from about 100 centipoiseto about 400 centipoise, from about 100 centipoise to about 300centipoise, from about 100 centipoise to about 200 centipoise, etc. Inaccordance with some embodiments, the pregelatinized starch can beprepared as an extruded starch, e.g., where starch is prepared bypregelatinization and acid-modification in one step in an extruder asdescribed in US 2015/0010767-A1, which extrusion method is herebyincorporated by reference.

If included, the starch can be present in any suitable amount. In someembodiments, the starch is present in the gypsum slurry in an amount offrom about 0% to about 20% by weight of the stucco, e.g., from about 0%to about 15% by weight of stucco, from about 0% to about 10% by weightof stucco, from about 0.1% to about 20% by weight of stucco, from about0.1% to about 15% by weight of stucco, from about 0.1% to about 10% byweight of stucco, from about 0.1% to about 6% by weight of stucco, fromabout 0.3% to about 4% by weight of stucco, from about 0.5% to about 4%by weight of stucco, from about 0.5% to about 3% by weight of stucco,from about 0.5% to about 2% by weight of stucco, from about 1% to about4% by weight of stucco, from about 1% to about 3% by weight of stucco,from about 1% to about 2% by weight of stucco, etc.

The gypsum slurry can optionally include at least one dispersant toenhance fluidity in some embodiments. The dispersants may be included ina dry form with other dry ingredients and/or in a liquid form with otherliquid ingredients in stucco slurry. Examples of dispersants includenaphthalenesulfonates, such as polynaphthalenesulfonic acid and itssalts (polynaphthalenesulfonates) and derivatives, which arecondensation products of naphthalenesulfonic acids and formaldehyde; aswell as polycarboxylate dispersants, such as polycarboxylic ethers, forexample, PCE211, PCE111, 1641, 1641F, or PCE 2641-Type Dispersants,e.g., MELFLUX 2641F, MELFLUX 2651F, MELFLUX 1641F, MELFLUX 2500Ldispersants (BASF), and COATEX Ethacryl M, available from Coatex, Inc.;and/or lignosultbnates or sulfonated lignin. Naphthalenesulfonatedispersants can be used to facilitate formation of larger bubbles andhence larger voids in the final product, and polycarboxylates such aspolycarboxylate ethers can be used to firm smaller bubbles and hencesmaller voids in the product. As void structure changes to the productare desired during manufacture, such dispersant adjustments and otherchanges in the process can be made as one of ordinary skill willappreciate. Lignosulfonates are water-soluble anionic polyelectrolytepolymers, byproducts from the production of wood pulp using sulfitepulping, One example of a lignin useful in the practice of principles ofembodiments of the present disclosure is Marasperse C-21 available fromReed Lignin Inc.

Lower molecular weight dispersants are generally preferred. Lowermolecular weight naphthalenesulfonate dispersants are favored becausethey trend to a lower water demand than the higher viscosity, highermolecular weight dispersants. Thus, molecular weights from about 3,000to about 10,000 (e.g., about 8,000 to about 10,000) are preferred. Asanother illustration, for PCE211 type dispersants, in some embodiments,the molecular weight can be from about 20,000 to about 60,000, whichexhibit less retardation than dispersants having molecular weight above60,000.

One example of a naphthalenesulfonate is DILOFLO, available from GEOSpecialty Chemicals. DILOFLO is a 45% naphthalenesulfonate solution inwater, although other aqueous solutions, for example, in the range ofabout 35% to about 55% by weight solids content, are also readilyavailable. Naphthalenesulfonates can be used in dry solid or powderform, such as LOMAR D, available from CEO Specialty Chemicals, forexample. Another example of naphthalenesulfonate is DAXAD, availablefrom GEO Specialty Chemicals.

If included, the dispersant can be provided in any suitable amount. Insome embodiments, for example, the dispersant is present in an amount,for example, from about 0% to about 0.7% by weight of stucco, 0% toabout 0.4%, by weight of stucco, about 0.05% to about 5% by weight ofthe stucco, from about 0.05% to about 0.3% by weight of stucco, or fromabout 1% to about 5% by weight of stucco.

In some embodiments, the gypsum slurry can optionally include one ormore phosphate-containing compounds, if desired, For example,phosphate-containing components useful in some embodiments includewater-soluble components and can be in the form of an ion, a salt, or anacid, namely, condensed phosphoric acids, each of which comprises two ormore phosphoric acid units; salts or ions of condensed phosphates, eachof which comprises two or more phosphate units; and monobasic salts ormonovalent ions of orthophosphates as well as water-soluble acyclicpolyphosphate salt. See, e.g., U.S. Pat. Nos. 6,342,284; 6,632,550;6,815,049; and 6,822,033.

Phosphate compositions if added in some embodiments can enhance greenstrength, resistance to permanent deformation (e.g., sag), dimensionalstability, etc. Trimetaphosphate compounds can be used, including, forexample, sodium trimetaphosphate, potassium trimetaphosphate, lithiumtrimetaphosphate, and ammonium trimetaphosphate. Sodium trimetaphosphate(STMP) is preferred, although other phosphates may be suitable,including for example sodium tetrametaphosphate, sodiumhexametaphosphate having from about 6 to about 27 repeating phosphateunits and having the molecular formula Na_(n+2)P_(n)O_(3n+1) whereinn=6−27, tetrapotassium pyrophosphate having the molecular formula K₄P₂O₇, trisodium dipotassium tripolyphosphate having the molecularformula Na₃K₂P₃O₁₀, sodium tripolyphosphate having the molecular formulaNa₅P₃O₁₀, tetrasodium pyrophosphate having the molecular formulaNa₄P₂O₇, aluminum trimetaphosphate having the molecular formulaAl(PO₃)₃, sodium acid pyrophosphate having the molecular formulaNa₂H₂P₂O₇, ammonium polyphosphate having 1,000-3,000 repeating phosphateunits and having the molecular formula (NH₄)_(n+2)P_(n)O_(3n+1), whereinn=1,000−3,000, or polyphosphoric acid having two or more repeatingphosphoric acid units and having the molecular formulaH_(n+2)P_(n)O_(3n+1) wherein n is two or more.

If included, the phosphate-containing compound can he present in anysuitable amount. To illustrate, in some embodiments, thephosphate-containing compound can be present in an amount, for example,from about 0.1% to about 1%, e.g*., about 0.2% to about 0.4% by weightof the stucco.

A water resistance or mold resistance additive such as siloxaneoptionally can be included. if included, in some embodiments, thesiloxane preferably is added in the form of an emulsion. The slurry isthen shaped and dried under conditions which promote the polymerizationof the siloxane to form a highly cross-linked silicone resin. A catalystwhich promotes the polymerization of the siloxane to form a highlycross-linked silicone resin can be added to the gypsum slurry. Asdescribed in U.S. Pat. No. 7,811,685, magnesium oxide can be included tocontribute to the catalysis and/or to the mold resistance and/or waterresistance in some embodiments. If included, magnesium oxide, is presentin any suitable amount, such as from about 0.02% to about 0.1%, e,g.,from about 0.02% to about 0.04% by weight of stucco.

In some embodiments, solventiess methyl hydrogen siloxane fluid soldunder the name SILRES BS 94 by Wacker-Chemie GmbH (Munich, Germany) canbe used as the siloxane, This product is a siloxane fluid containing nowater or solvents, It is contemplated that from about 0.05% to about0.5%, e.g., about 0.07% to about 0.14% of the BS 94 siloxane may be usedin some embodiments, based on the weight of the stucco. For example, insome embodiments, it is preferred to use from about 0.05% to about 0.2%,e.g., from about 0.09% to about 0.12% of the siloxane based on the drystucco weight.

The gypsum slurry can include any suitable fire resistant additive insome embodiments. Examples of suitable fire resistant additives includehigh expansion particulates, high efficiency heat sink additives,fibers, or the like, or any combination thereof, as described in U.S.Pat. No. 8,323,785, which description of such additives is herebyincorporated by reference. Vermiculite, aluminum trihydrate, glassfibers, and a combination thereof can be used in some embodiments.

For example, the high expansion particulates useful in accordance withsome embodiments can exhibit a volume expansion after heating for onehour at about 1560° F. (about 850° C.) of about 300% or more of theiroriginal volume. In some embodiments, high expansion vermiculites can beused that have a volume expansion of about 300% to about 380% of theiroriginal volume after being placed for one hour in a chamber having atemperature of about 1560° F. (about 850° C.). If included, highexpansion particulate, such as vermiculite, can be present in anysuitable amount. In some embodiments, it is present in an amount fromabout 1% to about 10%, e,g, about 3% to about 6% by weight of stucco.

Aluminum trihydrate (ATH), also known as alumina trihydrate and hydratedalumina, can increase fire resistance due to its crystallized orcompound water content. ATH is a suitable example of a high efficiencyheat sink additive. Such high efficiency heat sink (HEHS) additives havea heat sink capacity that exceeds the heat sink capacity of comparableamounts of gypsum dihydrate in the temperature range causing thedehydration and release of water vapor from the gypsum dihydratecomponent of the panel core. Such additives typically are selected fromcompositions, such as aluminum trihydrate or other metal hydroxides thatdecompose, releasing water vapor in the same or similar temperatureranges as does gypsum dihydrate. While other HEHS additives (orcombinations of HEHS additives) with increased heat sink efficiencyrelative to comparable amounts of gypsum dihydrate can be used,preferred HEHS additives provide a sufficiently-increased heat sinkefficiency relative to gypsum dihydrate to offset any increase in weightor other undesired properties of the HEHS additives when used in agypsum panel intended for fire rated or other high temperatureapplications. If included, heat sink additive, such as ATH, is presentin any suitable amount. In some embodiments, it is included in an amountfrom about 1% to about 8%, e.g., from about 2% to about 4% by -weight ofstucco.

The fibers may include mineral fibers, carbon and/or glass fibers andmixtures of such fibers, as well as other comparable fibers providingcomparable benefits to the panel. In some embodiments, glass fibers areincorporated in the gypsum core slurry and resulting crystalline corestructure. The glass fibers in some of such embodiments can have anaverage length of about 0.5 to about 0.75 inches and a diameter of about11 to about 17 microns. In other embodiments, such glass fibers may havean average length of about 0.5 to about 0.675 inches and a diameter ofabout 13 to about 16 microns. If included, fibers, such as glass fibers,is present in any suitable amount, such as, from about 0.1% to about 3%,e.g., from about 0.5% to about 1% by weight of stucco.

The gypsum board according to embodiments of the disclosure has utilityin a variety of different products having a range of desired densities,including, but not limited to, drywall (which can encompass such boardused not only for walls but also for ceilings and other locations asunderstood in the art), fire-rated board, mold-resistant board,water-resistant board, etc. Board weight is a function of thickness.Since boards are commonly made at varying thicknesses, board density isused herein as a measure of board weight. Examples of suitable thicknessinclude ⅜ inch, one-half inch, ⅝ inch, ¾ inch, or one inch, or in somecountries 9 mm, 9.5 mm, 10 mm, 12 mm, 12.5 mm, 13 mm, 15 mm, 20 mm, or25 mm. The advantages of the gypsum board in accordance with embodimentsof the disclosure can be seen at a range of densities, including up toheavier board densities, e.g., about 43 pcf or less, or 40 pcf or less,such as from about 17 pcf to about 43 pcf, from about 20 pcf to about 43pcf from about 24 pcf to about 43 pcf, from about 27 pcf to about 43pcf, from about 20 pcf to about 40 pcf, from about 24 pcf to about 40pcf, from about 27 pcf to about 40 pcf, from about 20 pcf to about 37pcf, from about 24 pcf to about 37 pcf, from about 27 pcf to about 37pcf, from about 20 pcf to about 35 pcf, from about 24 pcf to about 35pcf, from about 27 pcf to about 35 pcf, etc.

As noted herein, removing mass from gypsum wallboard has led toconsiderable difficulty in compensating for the concomitant loss instrength. In view of the improved foam void stability, some embodimentsof the disclosure surprisingly and unexpectedly enable the use of lowerweight board with good strength and/or desired fire or thermal property,lower water demand, and efficient use of additives as described herein.For example, in some embodiments, board density can be from about 17 pcfto about 35 pcf, e.g., from about 17 pcf to about 33 pcf, 17 pcf toabout 31 pcf, 17 pcf to about 28 pcf, from about 20 pcf to about 32 pcf,from about 20 pcf to about 31 pcf, from about 20 pcf to about 30 pcf,from about 20 pcf to about 30 pcf, from about 20 pcf about 29 pcf, fromabout 20 pcf to about 28 pcf, from about 21 pcf to about 33 pcf, fromabout 21 pcf to about 32 pcf, from about 21 pcf to about 33 pcf, fromabout 21 pcf to about 32 pcf, from about 21 pcf to about 31 pcf fromabout 21 pcf to about 30 pcf, from about 21 pcf to about 29 pcf, fromabout 21 pcf to about 28 pcf, from about 21 pcf to about 29 pcf, fromabout 24 pcf to about 33 pcf, from about 24 pcf to about 32 pcf, fromabout 24 pcf to about 31 pcf, from about 24 pcf to about 30 pcf, fromabout 24 pcf to about 29 pcf, from about 24 pcf to about 28 pcf, or fromabout 24 pcf to about 27 pcf, etc.

The cover sheets can be in any suitable form. It will be understoodthat, with respect to cover sheets, the terms “face” and “top” sheetsare used interchangeably herein, while the terms “back” and “bottom” arelikewise used interchangeably herein. For example, the cover sheets maycomprise cellulosic fibers, glass fibers, ceramic fibers, mineral wool,or a combination of the aforementioned materials. One or both of thesheets may comprise individual sheets or multiple sheets. In preferredembodiments, the cover sheets comprise a cellulosic fiber. For example,paper sheet, such as Manila paper or kraft paper, can be used as theback sheet. Useful cover sheet paper includes Manila 3-ply, Manila7-ply, News-Line 3-ply, or News-Line 7-ply available from United StatesGypsum Corporation, Chicago, Ill.; and Manila heavy paper and MH ManilaHT (high tensile) paper, available from United States GypsumCorporation, Chicago, Ill.

In addition, the cellulosic paper can comprise any other material orcombination of materials. For example, one or both sheets, particularlythe face (top) sheet can include polyvinyl alcohol, boric acid, orpolyphosphate as described herein (e.g., sodium trimetaphosphate) toenhance the strength of the paper. In sonic embodiments, the paper canbe contacted with a solution of one or more of polyvinyl alcohol, bodeacid, and/or polyphosphate so that the paper is at least partiallywetted. The paper can be at least partially saturated in someembodiments. The polyvinyl alcohol, boric acid and/or boric acid canpenetrate the fibers in the paper in some embodiments. The solution ofpolyvinyl alcohol, boric acid, and/or polyphosphate can be in anysuitable amount and can be applied in any suitable manner as will beappreciated in the art. For example, the solution can be in the form offrom about 1% to about 5% solids by weight in water of each ingredientpresent between the polyvinyl alcohol, the boric acid and/orpolyphosphate, which can be added in one solution or if desired inmultiple solutions,

In some embodiments, one or both sheets can comprise glass fibers,ceramic fibers, mineral wool, or a combination of the aforementionedmaterials. One or both sheets in accordance with the present disclosurecan be generally hydrophilic, meaning that the sheet is at leastpartially capable of adsorbing water molecules onto the surface of thesheet and/or absorbing water molecules into the sheet.

In other embodiments, the cover sheets can be “substantially free” ofglass fibers ceramic fibers, mineral wool, or a mixture thereof, whichmeans that the cover sheets contain either (i) 0 wt. % based on theweight of the sheet, or no such glass fibers ceramic fibers, mineralwool, or a mixture thereof, or (ii) an ineffective or (iii) animmaterial amount of glass fibers ceramic fibers, mineral wool, or amixture thereof. An example of an ineffective amount is an amount belowthe threshold amount to achieve the intended purpose of using glassfibers ceramic fibers, mineral wool, or a mixture thereof, as one ofordinary skill in the art will appreciate. An immaterial amount may be,e.g., below about 5 wt. %, such as below about 2 wt. %, below about 1wt. %, below about 0.5 wt. %, below about 0.2 wt. %, below about 0.1 wt.%, or below about 0.01 wt. % based on the weight stucco as one ofordinary skill in the art will appreciate. However, if desired inalternative embodiments, such ingredients can be included in the coversheets.

some embodiments, the thermal conductivity of the top and/or bottomsheet is less than about 0.1 w/(m.k.). For example, the thermalconductivity of the top and/or bottom sheet is less than about 0.05w/(m.k.).

If desired, in some embodiments, one or both cover sheets can optionallyinclude any suitable amount of inorganic compound or mixture ofinorganic compounds that adequately imparts greater fire endurance wheresuch properties are sought. Examples of suitable inorganic compoundsinclude aluminum trihydrate and magnesium hydroxide. For example, thecover sheets can comprise any inorganic compound or mixture of inorganiccompounds with high crystallized water content, or any compound thatreleases water upon heating. In some embodiments, the amount ofinorganic compound or the total mixture of inorganic compounds in thesheet ranges from about 0.1% to about 30% by weight of the sheet. Theinorganic compound or inorganic compounds used in the sheet may be ofany suitable particle size or suitable particle size distribution.

In some embodiments, ATH can be added in an amount from about 5% toabout 30% by total weight of the sheet. ATH typically is very stable atroom temperature. Above temperatures between about 180° C. and 205° C.,ATH typically undergoes an endothermic decomposition releasing watervapor. The heat of decomposition for such ATH additives is greater thanabout 1000 Joule/gram, and in one embodiment is about 1170 Joule/gram.Without being bound by theory, it is believed that the ATH additivedecomposes to release approximately 35% of the water of crystallizationas water vapor when heated above 205° C. in accordance with thefollowing equation: Al(OH)₃→Al₂O₃+3H₂O.

A cover sheet comprising inorganic particles of high water content, suchas ATH, can increase fire endurance of the board. The inorganic compoundor mixture of compounds is incorporated into the sheet in someembodiments. A cover sheet such as paper comprising ATH can be preparedby first diluting cellulosic fiber in water at about 1% consistency,then mixing with ATH particles at a predetermined ratio. The mixture canbe poured into a mold, the bottom of which can have a wire mesh to drainoff water. After draining, fiber and ATH particles are retained on thewire. The wet sheet can be transferred to a blotter paper and dried atabout 200-360° F.

In some embodiments, as described for inclusion in the cover sheet or ina stucco slurry, e.g., ATH particles of less than about 20 μm arepreferred, but any suitable source or grade of ATH can be used. Forexample, ATH can be obtained from commercial suppliers such as Huberunder the brand names SB 432 (10 μm) or Hydra® 710 (1 μm).

In some embodiments, the cover sheet may comprise magnesium hydroxide.In these embodiments, the magnesium hydroxide additive preferably has aheat of decomposition greater than about 1000 Joule/gram, such as about1350 Joule/gram, at or above 180° C. to 205° C. In such embodiments, anysuitable magnesium hydroxide can be used, such as that commerciallyavailable from suppliers, including Akrochem Corp. of Akron, Ohio.

In other embodiments, the cover sheets be “substantially free” ofinorganic compounds such as ATH, magnesium hydroxide, or a mixturethereof, which means that the cover sheets contain either (i) 0 wt. %based on the weight of the sheet, or no such inorganic compounds such asATH, magnesium hydroxide, or a mixture thereof, or (ii) an ineffectiveor (iii) an immaterial amount of inorganic compounds such as ATH,magnesium hydroxide, or a mixture thereof. An example of an ineffectiveamount is an amount below the threshold amount to achieve the intendedpurpose of using inorganic compounds such as ATH, magnesium hydroxide,or a mixture thereof, as one of ordinary skill in the art willappreciate. An immaterial amount may be, e.g., below about 5 wt. %, suchas below about 2 wt. %, below about 1 wt. %, below about 0.5 wt. %,below about 0.1 wt. %, below about 0.05 wt. %, below about 0.01 wt. %,etc.

The cover sheets can also have any suitable total thickness. In someembodiments, at least one of the cover sheets has a relatively highthickness, e.g., a thickness of at least about 0.014 inches. in someembodiments, it is preferred that there is an even higher thickness,e.g., at east about 0.015 inches, at least about 0.016 inches, at leastabout 0.017 inches, at least about 0.018 inches, at least about 0.019inches, at least about 0.020 inches, at least about 0.021 inches, atleast about 0.022 inches, or at least about 0.023 inches. Any suitableupper limit for these ranges can be adopted, e.g., an upper end of therange of about 0.030 inches, about 0.027 inches, about 0.025 inches,about 0.024 inches, about 0.023 inches, about 0.022 inches, about 0.021inches, about 0.020 inches, about 0.019 inches, about 0.018 inches, etc.The total sheet thickness refers to the sum of the thickness of eachsheet attached to the gypsum board.

The cover sheets can have any suitable density. For example, in someembodiments, at least one or both of the cover sheets has a density ofat least about 36 pcf, e.g., from about 36 pcf to about 46 pcf, such asfrom about 36 pcf to about 44 pcf, from about 36 pcf to about 42 pcf,from about 36 pcf about 40 pcf, from about 38 pcf to about 46 pcf, fromabout 38 pcf to about 44 pcf, from about 38 pcf to about 42 pcf, etc.

The cover sheet can have any suitable weight. For example, in someembodiments, lower basis weight cover sheets (e.g., formed from paper)such as, for example, at least about 33 lbs/MSF (e.g., from about 33lbs/MSF to about 65 lbs/MSF, from about 33 lbs/MSF to about 60 lbs/MSF,33 lbs/MSF to about 58 lbs/MSF from about 33 lbs/MSF to about 55lbs/MSF, from about 33 lbs/MSF to about 50 lbs/MSF, from about 33lbs/MSF to about 45 lbs/MSF, etc, or less than about 45 lbs/MSF)) can beutilized in some embodiments. In other embodiments, one or both coversheets has a basis weight from about 38 lbs/MSF to about 65 lbs/MSF,from about 38 lbs/MSF to about 60 lbs/MSF, from about 38 lbs/MSF toabout 58 lbs/MSF, from about 38 lbs/MSF to about 55 lbs/MSF, from about38 lbs/MSF to about 50 lbs/MSF, from about 38 lbs/MSF to about 45lbs/MSF.

However, if desired, in some embodiments, even heavier basis weights canbe used, e.g., to further enhance nail pull resistance or to enhancehandling, e.g., to facilitate desirable “feel” characteristics forend-users. Thus, one or both of the cover sheets can have a basis weightof, for example, at least about 45 lbs/MSF (e.g., from about 45 lbs/MSFto about 65 lbs/MSF, from about 45 lbs/MSF to about 60 lbs/MSF, fromabout 45 lbs/MSF to about 55 lbs/MSF, from about 50 lbs/MST to about 65lbs/MSF, from about 50 lbs/MSF to about 60 lbs/MSF, etc.). If desired,in some embodiments, one cover sheet (e.g., the “face” paper side wheninstalled) can have the aforementioned higher basis weight, e.g., toenhance nail pull resistance and handling, while the other cover sheet(e.g., the “back” sheet when the board is installed) can have somewhatlower weight basis if desired (e.g., weight basis of less than about 60lbs/MSF, e.g., from about 33 lbs/MSF to about 55 lbs/MSF, from about 33lbs/MSF to about 50 lbs/MSF, from about 33 lbs/MSF to about 45 lbs/MSF,or from about 33 lbs/MSF to about 40 lbs/MSF).

In some embodiments, the gypsum board product exhibits fire resistancebeyond what is found in conventional wallboard. To achieve fireresistance, the board can optionally be formed from certain additivesthat enhance fire resistance in the final board product, as describedherein. Some fire resistant board is considered “fire rated” when theboard passes certain tests while in an assembly.

In some embodiments, the gypsum board containing fire-resistant additivecan pass certain tests using a small scale bench test, in accordancewith ASTM C1795-15, including high temperature shrinkage in the x-ydirections (width-length), high temperature shrinkage (or evenexpansion) in the z-direction (thickness), and a Thermal InsulationIndex (TI). Such bench tests are suitable for predicting the fireresistance performance of the gypsum board, e.g., in full scale testsunder ASTM E119-09a for assemblies constructed under any of UL U305,U419, and/or U423 (2015 editions), and/or equivalent fire testprocedures and standards. Passing the ASTM E119-09a test with theassembly of any one of these UL tests allows for a fire-rating. Briefly,UL U305 calls for wood studs in the assembly. UL U419 is a non-loadbearing metal stud assembly, using 25 gauge studs. UL U423 is a loadbearing metal stud assembly using 20 gauge studs. UL U419 is generallyconsidered a more difficult test to pass than UL U305 or UL U423 becauseit uses light gauge steel studs that deform more easily than the studsused under UL U305 and UL U423.

In accordance with some embodiments, gypsum board is configured to meetor exceed a fire rating pursuant to the fire containment and structuralintegrity requirements of assemblies constructed under one or more of ULU305, U419, and/or U423, using ASTM E119, and/or equivalent fire testprocedures and standards, e.g., where the board contains fire resistantadditives discussed herein. The present disclosure thus provides gypsumboard (e.g., reduced weight and density at thickness of ½ inch or ⅝inch), and methods for making the same, that are capable of satisfyingfire ratings (e.g., 17 min., 20 min., 30 min., ¾ hour, one-hour,two-hour, etc.) pursuant to the fire containment and structuralintegrity procedures and standards of various UL standards such as thosediscussed herein, in some embodiments.

The gypsum board can be tested, e.g., in an assembly according toUnderwriters Laboratories UL 0305, U419, and U423 specifications and anyother fire test procedure that is equivalent to any one of those firetest procedures. It should be understood that reference made herein to aparticular fire test procedure of ASTM E-119 and using assembliesprepared in accordance with Underwriters Laboratories, such as, UL U305,U419, and U423, for example, also includes a fire test procedure, suchas one promulgated by any other entity, that is equivalent to ASTME119-09a and the particular UL standard in question.

For example, the gypsum board in some embodiments is effective toinhibit the transmission of heat through an assembly constructed inaccordance with any one of UL Design Numbers U305, U41 9 or U423, theassembly having a first side with a single layer of gypsum boards and asecond side with a single layer of gypsum boards. ASTM E119-09a involvesplacing thermocouples in numerous places throughout a particularassembly. The thermocouples then monitor temperature as the assembly isexposed to heat over time, in this respect, surfaces of gypsum boards onthe first side of the assembly are heated in accordance with thetime-temperature curve of ASTM E119-09a, while surfaces of gypsum panelson the second side of the assembly are provided with temperature sensorspursuant to ASTM E119-09a. ASTM E119 specifies that the assembly failsthe test if any of the thermocouples exceeds a certain presettemperature (ambient plus 325° F.), or if the average of thetemperatures from the thermocouples exceeds a different presettemperature (ambient plus 250° F.).

In some embodiments of fire resistant board, when heated, the maximumsingle value of the temperature sensors is less than about 325° F. plusambient temperature after about 50 minutes, and/or or the average valueof the temperature sensors is less than about 250° F. plus ambienttemperature after about 50 minutes. In sonic embodiments, the board hasa density of about 40 pounds per cubic foot or less. Desirably, theboard has good strength as described herein, such as a core hardness ofat least about 11 pounds (5 kg), e,g., at least about 13 pounds (5.9kg), or at least about 15 pounds (6.8 kg).

In some embodiments, when the surfaces on the first side of the assemblyof fire resistant gypsum board with fire resistant additive are heated,the maximum single value of the temperature sensors is less than about325° F. plus ambient temperature after about 55 minutes, and/or theaverage value of the temperature sensors is less than about 250° F. plusambient temperature after about 55 minutes. In other embodiments, whenthe surfaces of gypsum board on the first side of the assembly areheated the maximum single value of the temperature sensors is less thanabout 325° F. plus ambient temperature after about 60 minutes and/or theaverage value of the temperature sensors is less than about 250° F. plusambient temperature after about 60 minutes. In other embodiments, whenthe surfaces of gypsum panels on the first side of the assembly areheated, the maximum single value of the temperature sensors is less thanabout 325° F. plus ambient temperature after about 50 minutes, and/orthe average value of the temperature sensors is less than about 250° F.plus ambient temperature after about 50 minutes. In other embodiments,when the surfaces of gypsum boards on the first side of the assembly areheated, the maximum single value of the temperature sensors is less thanabout 325° F. plus ambient temperature after about 55 minutes, and/orthe average value of the temperature sensors is less than about 250° F.plus ambient temperature after about 55 minutes. In other embodiments,when the surfaces of gypsum boards on the first side of the assembly areheated, the maximum single value of the temperature sensors is less thanabout 325° F. plus ambient temperature after about 60 minutes, and theaverage value of the temperature sensors is less than about 250° F. plusambient temperature after about 60 minutes.

In some embodiments, fire resistant gypsum board with fire resistantadditive is effective to inhibit the transmission of heat through theassembly when constructed in accordance with. DE, Design. Number U305 soas to achieve a one hour fire rating under ASTM E119-09a. In someembodiments, the board is effective to inhibit the transmission of heatthrough the assembly when constructed in accordance with UL DesignNumber 15419 so as to achieve a one hour fire rating under ASTME119-09a. In some embodiments, the gypsum board is effective to inhibitthe transmission of heat through the assembly when constructed inaccordance with U L Design Number U423 so as to achieve a one hour firerating under ASTM E119-09a, in some embodiments, the board has a Thermalinsulation Index (TI) of about 20 minutes or greater and/or a HighTemperature Shrinkage (S) of about 10% or less, in accordance with ASTMC1795-1 5. In some embodiments, the board has a ratio of HighTemperature Thickness Expansion (JE) to S (TE/S) of about 0.06 or more,e.g., about 0.2 or more.

Furthermore, in some embodiments, the gypsum board can be in the form ofreduced weight and density, fire resistant gypsum board with HighTemperature Shrinkage of less than about 10% in the x-y directions(width-length) and High Temperature. Thickness Expansion in thez-direction (thickness) of greater than about 20% when heated to about1560° F. (850° C.). In yet other embodiments, when used in wall or otherassemblies, such assemblies have fire testing performance comparable toassemblies made with heavier, denser commercial fire rated panels. Insome embodiments, the. High Temperature Shrinkage of the panelstypically is less than about 10% in the x-y directions (width-length).In some embodiments, the ratio of z-direction High Temperature ThicknessExpansion to x-y High Temperature Shrinkage is at least about 2 to overabout 17 at 1570° F. (855° C.).

In some embodiments, a fire resistant gypsum board formed according toprinciples of the present disclosure, and the methods for making same,can provide a panel that exhibits an average shrink resistance of about85% or greater when heated at about 1800 (980° C.) for one hour. Inother embodiments, the gypsum board exhibits an average shrinkresistance of about 75% or greater when heated at about 1800° F. (980°C.) for one hour.

The gypsum layers between the cover sheets can be effective to provide aThermal Insulation Index (TI) of about 20 minutes or greater. The boardcan have a desired density (I)) as described herein. The gypsum layersbetween the cover sheets can be effective to provide the gypsum boardwith a ratio of TI/D of about 0.6 minutes/pounds per cubic foot (0.038minutes/(kg/m³)) or more.

in some embodiments, gypsum board made according to the disclosure meetstest protocols according to ASTM Standard C473-10, For example, in someembodiments, when the board is cast at a thickness of 1/2 inch, theboard has a nail pull resistance of at least about 65 lb_(f) (poundsforce, which is sometimes referred to as simply “lb” or “lbs” forconvenience by those of ordinary skill in the art, who understand thisis a measurement of force) as determined according to ASTM C473-10(method B), e.g., at least about 68 lb_(f), at least about 70 lb_(f), atleast about 72 lb_(f), at least about 74 lb_(f), at least about 75lb_(f), at least about 76 lb_(f), at least about 77 lb_(f), etc. Invarious embodiments, the nail pull resistance can be from about 65lb_(f), to about 100 lb_(f), from about 65 lb_(f) to about 95 lb_(f),from about 65 lb_(f) to about 90 lb_(f), from about 65 lb_(f) to about85 lb_(f), from about 65 lb_(f) to about 80 lb_(f), from about 65 lb_(f)to about 75 lb_(f), from about 68 lb_(f) to about 100 lb_(f), from about68 lb_(f) to about 95 lb_(f), from about 68 lb_(f) to about 90 lb_(f),from about 68 lb_(f) to about 85 lb_(f), from about 68 lb_(f) to about80 lb_(f), from about 70 lb_(f) to about 100lb_(f), from about 70 lb_(f)to about 95 lb_(f), from about 70 lb_(f) to about 90 lb_(f), from about70 lb_(f) to about 85 lb_(f), from about 70 lb_(f) to about 80 lb_(f),from about 72 lb_(f) to about 100 lb_(f), from about 72 lb_(f) to about95 lb_(f), from about 72 lb_(f) to about 90 lb_(f), from about 72 lb_(f)to about 85 lb_(f), from about 72 lb_(f) to about 80 lb_(f), from about72 lb_(f) to about 77 lb_(f), from about 72 lb_(f) to about 75 lb_(f),from about 75 lb_(f) to about 100 lb_(f), from about 75 lb_(f) to about95 lb_(f), from about 75 lb_(f) to about 90 lb_(f), from about 75lb_(f), to about 85 lb_(f), from about 75 lb_(f) to about 80 lb_(f),from about 75 lb_(f) to about 77 lb_(f), from about 77 lb_(f) to about100 lb_(f), from about 77 lb_(f) to about 95 lb_(f), from about 77lb_(f) to about 90 lb_(f), from about 77 lb_(f) to about 85 lb_(f), orfrom about 77 lb_(f) to about 80 lb_(f).

With respect to flexural strength, in some embodiments, when cast in aboard of one-half inch thickness, the board has a flexural strength ofat least about 36 lb_(f) in a machine direction (e.g., at least about 38lb_(f), at least about 40 lb_(f), etc) and/or at least about 107 lb_(f)(e.g., at least about 110 lb_(f), at least about 112 lb_(f), etc.) in across-machine direction as determined according to the ASTM standardC473-10, method B. In various embodiments, the board can have a flexuralstrength in a machine direction of from about 36 lb_(f) to about 60lb_(f), e.g., from about 36 lb_(f) to about 55 lb_(f), from about 36lb_(f) to about 50 lb_(f), from about 36 lb_(f) to about 45 lb_(f), fromabout 36 lb_(f) to about 40 lb_(f), from about 36 lb_(f) to about 38lb_(f), from about 38 lb_(f) to about 60 lb_(f), from about 38 lb_(f) toabout 55 lb_(f), from about 38 lb_(f) to about 50 lb_(f), from about 38lb_(f) to about 45 lb_(f), from about 38 lb_(f) to about 40 lb_(f), fromabout 40 lb_(f) to about 60 lb_(f), from about 40 lb_(f) to about 55lb_(f), from about 40 lb_(f) to about 50 lb_(f), or from about 40 lb_(f)to about 45 lb_(f). In various embodiments, the board can have aflexural strength in a cross-machine direction of from about 107 lb_(f)to about 130 lb_(f), e.g., from about 107 lb_(f) to about 125 lb_(f),from about 107 lb_(f) to about 120 lb_(f), from about 107 lb_(f) toabout 115 lb_(f), from about 107 lb_(f) to about 112 lb_(f), from about107 lb_(f) to about 110 lb_(f), from about 110 lb_(f) to about 130lb_(f), from about 110 lb_(f) to about 125 lb_(f), from about 110 lb_(f)to about 120 lb_(f), from about 110 lb_(f) to about 115 lb_(f), fromabout 110 lb_(f) to about 112 lb_(f), from about 112 lb_(f) to about 130lb_(f), from about 112 lb_(f) to about 125 lb_(f), from about 112 lb_(f)to about 120 lb_(f), or from about 112 lb_(f) to about 115 lb_(f).

In addition, in some embodiments, board can have an average corehardness of at least about 11 lb_(f), e.g., at least about 12 lb_(f), atleast about 13 lb_(f), at least about 14 lb_(f), at least about 15lb_(f), at least about 16 lb_(f), at least about 17 lb_(f), at leastabout 18 lb_(f), at least about 19 lb_(f), at least about 20 lb_(f), atleast about 21 lb_(f), or at least about 22 lb_(f), as determinedaccording to ASTM C473-10, method B. In some embodiments, board can havea core hardness of from about 11 lb_(f) to about 25 lb_(f), e.g., fromabout 11 lb_(f) to about 22 lb_(f), from about 11 lb_(f) to about 21lb_(f), from about 11 lb_(f) to about 2.0 lb_(f), from about 11 lb_(f)to about 19 lb_(f), from abbut 11 lb_(f) to about 18 lb_(f), from about11 lb_(f) to about 17 lb_(f), from about 11 lb_(f) to about 16 lb_(f),from about 11 lb_(f) to about 15 lb_(f), from about 11 lb_(f) to about14 lb_(f); from about 11 lb_(f) to about 13 lb_(f), from about 11 lb_(f)to about 12 lb_(f), from about 12 lb_(f) to about 25 lb_(f), from about12 lb_(f) to about 22 lb₁, from about 12 lb_(f) to about 21 lb_(f), fromabout 12 lb_(f) to about 20 lb_(f), from about 12 lb_(f) to about 19lb_(f), from about 12 lb_(f) to about 18 lb_(f), from about 12 lb_(f) toabout 17 lb_(f), from about 12 lb_(f) to about 16 lb_(f), from about 12lb_(f) to about 15 lb_(f), from about 12 lb_(f) to about 14 lb_(f), fromabout 12 lb_(f) to about 13 lb_(f), from about 13 lb_(f) to about 25lb_(f), from about 13 lb_(f) to about 22 lb_(f), from about 13 lb_(f) toabout 21 lb_(f), from about 13 lb_(f) to about 20 lb_(f), from about 13lb_(f) to about 19 lb_(f), from about 13 lb_(f) to about 18 lb_(f), fromabout 13 lb_(f) to about 17 lb_(f), from about 13 lb_(f) to about 16lb_(f); from about 13 lb_(f) to about 15 lb_(f), from about 13 lb_(f) toabout 14 lb_(f), from about 14 lb_(f) to about 25 lb_(f), from about 14lb_(f) to about 22 lb_(f), from about 14 lb_(f) to about 21 lb_(f), fromabout 14 lb_(f) to about 20 lb_(f), from about 14 lb_(f) to about 19lb_(f), from about 14 lb_(f) to about 18 lb_(f), from about 14 lb_(f) toabout 17 lb_(f), from about 14 lb_(f) to about 16 lb_(f), from about 14lb_(f) to about 15 lb_(f), from about 15 lb_(f) to about 25 lb_(f), fromabout 15 lb_(f) to about 22 lb_(f), from about 15 lb_(f) to about 21lb_(f); from about 15 lb_(f) to about 20 lb_(f), from about 15 lb_(f) toabout 19 lb_(f), from about 15 lb_(f) to about 18 lb_(f), from about 15lb_(f) to about 17 lb_(f), from about 15 lb_(f) to about 16 lb_(f), fromabout 16 lb_(f) to about 25 lb_(f), from about 16 lb_(f) to about 22lb_(f), from about 16 lb_(f) to about 21 lb_(f), from about 16 lb_(f) toabout 20 lb_(f), from about 16 lb_(f) to about 19 lb_(f), from about 16lb_(f) to about 18 lb_(f), from about 16 lb_(f) to about 17 lb_(f), fromabout 17 lb_(f) to about 25 lb₁, from about 17 lb_(f) to about 22lb_(f), from about 17 lb_(f) to about 21 lb_(f), from about 17 lb_(f) toabout 20 lb_(f), from about 17 lb_(f) to about 19 lb_(f), from about 17lb_(f) to about 18 lb_(f), from about 18 lb_(f) to about 25 lb_(f), fromabout 18 lb_(f) to about 22 lb_(f), from about 18 lb_(f) to about 21lb_(f), from about 18 lb_(f) to about 20 lb_(f), from about 18 lb_(f) toabout 19 lb_(f), from about 19 lb_(f) to about 25 lb_(f), from about 19lb_(f) to about 22 lb_(f), from about 19 lb_(f) to about 21 lb_(f), fromabout 19 lb_(f) to about 20 lb_(f), from about 21 lb_(f) to about 25lb_(f), from about 21 lb_(f) to about 22 lb_(f), or from about 22 lb_(f)to about 25 lb_(f).

Product according to embodiments of the disclosure can be made ontypical manufacturing lines. For example, board manufacturing techniquesare described in, for example, U.S. Pat. No. 7,364,676 and U.S. PatentApplication Publication 2010/0247937. Briefly, in the case of gypsumboard, the process typically involves discharging a cover sheet onto amoving conveyor. Since gypsum board is normally formed “face down,” thiscover sheet is the “face” cover sheet in such embodiments,

Dry and/or wet components of the gypsum slurry are fed to a mixer (e.g.,a pin or pinless mixer), where they are agitated to form the gypsumslurry. The mixer comprises a main body and a discharge conduit (e.g., agate-canister-boot arrangement as known in the art, or an arrangement asdescribed in U.S. Pat. Nos. 6,494,609 and 6,874,930). In someembodiments, the discharge conduit can include a slurry distributor witheither a single feed inlet or multiple feed inlets, such as thosedescribed in U.S. Patent Application Publication 2012/0168527 A1 andU.S. Patent Application Publication 2012/0170403 A1, for example. Inthose embodiments, using a slurry distributor with multiple feed inlets,the discharge conduit can include a suitable flow splitter, such asthose described in U.S. Patent Application Publication 2012/0170403 A1.Foaming agent can be added in the discharge conduit of the mixer (e.g.,in the gate as described, for example, in U.S. Pat. Nos. 5,683,635 and6,494,609) or in the main body if desired. Slurry discharged from thedischarge conduit after all ingredients have been added, includingfoaming agent, is the primary gypsum slurry and will form the boardcore. This board core slurry is discharged onto the moving face coversheet.

The face cover sheet may bear a thin skim coat in the form of arelatively dense layer of slurry. Also, hard edges, as known in the art,can be formed, e.g., from the same slurry stream forming the face skimcoat. In embodiments where foam is inserted into the discharge conduit,a stream of secondary gypsum slurry can be removed from the mixer bodyto form the dense skim coat slurry, which can then be used to form theface skim coat and hard edges as known in the art. If included, normallythe face skim coat and hard edges are deposited onto the moving facecover sheet before the core slurry is deposited, usually upstream of themixer. After being discharged from the discharge conduit, the coreslurry is spread, as necessary, over the face cover sheet (optionallybearing skim coat) and covered with a second cover sheet (typically the“back” cover sheet) to form a wet assembly in the form of a sandwichstructure that is a board precursor to the final product. The secondcover sheet may optionally bear a second skim coat, which can be formedfrom the same or different secondary (dense) gypsum slurry as for theface skim coat, if present. The cover sheets may be formed from paper,fibrous mat or other type of material (e.g., foil plastic, glass mat,non-woven material such as blend of cellulosic and inorganic filler,etc.).

The wet assembly thereby provided is conveyed to a forming station wherethe product is sized to a desired thickness (e.g., via forming plate),and to one or more knife sections where it is cut to a desired length.The wet assembly is allowed to harden to form the interlockingcrystalline matrix of set gypsum, and excess water is removed using adrying process (e.g., by transporting the assembly through a kiln).Surprisingly and unexpectedly, it has been found that board preparedaccording to embodiments of the disclosure with pregelatinized,partially hydrolyzed starch prepared in accordance with embodiments ofthe disclosure requires significantly less time in a drying processbecause of the low water demand characteristic of the starch. This isadvantageous because it reduces energy costs.

In some embodiments, the fatty alcohol of the invention can be used tostabilize the foaming agent of the board core in a composite boardhaving a concentrated layer as described in U.S. Applications62/184,060, 62/290,361, and 15/186,176, incorporated herein byreference. For example, the fatty alcohol and foaming agent can be usedto prepare the low density board core, with additives more concentratedin the concentrated layer, using the ingredients, amounts, boarddimensions, and methods of productions described in U.S. Application62/184,060, 62/290,361, and 15/186,176.

In some embodiments, the fatty alcohol can be used in cement boardproducts. The cement can be formed from a core mix of water and a cementmaterial (e.g., Portland cement, alumina cement, magnesia cement, etc.,and blends of such materials). A foaming agent and the fatty alcohol arealso included in the mix. Optionally, light-weight aggregate (e.g.,expanded clay, expanded slag, expanded shale, perlite, expanded glassbeads, polystyrene beads, and the like) can be included in the mix insome embodiments. Other additives that can be used in forming the cementboard include, for example, dispersant, fiber (e.g., glass, cellulosic,PVC, etc.), accelerator, retarder, pozzolanic material, calcium sulfatehemihydrate (e.g., calcium sulfate alpha hemihydrate), filler, etc., orcombinations thereof.

The fatty alcohol can be used in a method of forming foamed cementslurry. The method comprises, consists of, or consists essentially ofcombining foaming agent with fatty alcohol to form an aqueous soapmixture; generating a foam from the aqueous soap mixture; and adding thefoam to a cement slurry comprising cement (e.g., Portland cement,alumina cement, magnesia cement, etc., or combinations thereof) andwater to form the foamed cement slurry. As the foam is entrained in thecement slurry, foam bubbles are formed with a shell surrounding thebubbles interfacing the slurry. Without wishing to be bound by anyparticular theory, the presence of fatty alcohol is believed todesirably stabilize the shell at the interface. Other additives can alsobe added to the cement slurry, such as, for example, dispersant, fiber(e.g., glass, cellulosic, PVC, etc.), accelerator, retarder, pozzolanicmaterial, calcium sulfate hemihydrate (e.g., calcium sulfate alphahemihydrate), filler, etc., or combinations thereof. Methods ofpreparing cement boards (and additives included therein) are describedin, for example, U.S. Pat. Nos. 4,203,788; 4,488,909; 4,504,335;4,916,004; 6,869,474; and 8,070,878.

The cement slurry comprising, consisting, or consisting essentially ofwater, cement, foaming agent, and a fatty alcohol can have increasedstrength compared to the same board formed without the fatty alcohol,when the slurry is formed and dried as board.

The following example(s) further illustrate the invention but, ofcourse, should not be construed as in any way limiting its scope.

EXAMPLE 1

This example demonstrates the effect of fatty alcohols on the foamingproperties of foaming agents, with and without the presence ofpolycarboxylate dispersant.

In particular, banning, surface tension, and stability experiments werecarried out on lip arcing agent solutions. Three types of foaming agents(soaps) were tested. Foaming Agent IA was a stable soap, in the form ofCS230, which is a lauryl ether sulfate blend, commercially availablefrom Stepan (Northfield, Ill.), in addition, two unstable soaps weretested, identified as Foaming Agent 1B and Foaming Agent 1C. FoamingAgent 1B was Polystep B25, which is an alkyl sulfate blend, commerciallyavailable from Stepan, and Foaming Agent 1C was Hyonic 25AS, which is analkyl sulfate blend, commercially available from Ceo Specialty Chemicals(Ambler, Pa.). Each foaming agent acts as a surfactant and hence formedtried a surfactant solution since they require water.

Surfactant solution modifications were conducted by adding a fattyalcohol in some samples as indicated in FIGS. 2-5 and Table 1. The fattyalcohols that were tested were 1-octanol, 1-decanol, and 1-dodecanol.Each solution contained 30 wt. % surfactant and 1 wt. % fatty alcohol(where present). Some solutions were further modified by addition of 0.1wt. % (1000 ppm) of polycarboxylate ether (PCE) dispersant in the formof Ethacryl commercially available from Coatex Group, Genay, France. ThePCE was included to evaluate the impact of soap modifiers on systemswith a surface active polymeric dispersant used in gypsum products. Thebalance of each solution was water. Foaming studies were conducted byshaking (by hand) 10 ml of surfactant solution in a vial for 60 secondsand reporting the (barn height in mm.

FIGS. 1-3 are bar graphs that illustrate the foaming results. FIG. 1shows the results of foam generated with stable soap and unstable soapsboth alone and in the presence of 1000 ppm of polycarboxylate etherdispersant in the form of Ethacryl M™ (Coatex). FIG. 1 shows that polycarboxylates have a strong influence on foaming of both unstable soaps.

FIGS. 2 and 3 illustrate foam generated with 1 wt. % fatty alcoholmodified unstable surfactant solutions (Foaming Agents 1B and 1C,respectively), alone, or with 1000 ppm of polycarboxylate etherdispersant in the form of Ethacryl M™ (Coatex). FIGS. 2-3 demonstratethat soap modification with 1 wt. % of fatty alcohol changed the foamingproperties of the unstable soaps. In particular, a more robust foamstructure was produced in the presence of the fatty alcohols, asdemonstrated by the fatty alcohols reducing the relative impact of thepolycarboxylate on foaming. A lower foam height was desired because itindicates a reduced relative surface activity of polycarboxylates. Inthe ease of decanol, foaming was even reduced with PCF in the solution.The decanol gave a lower foam height because the surfactant-fattyalcohol complex had a higher affinity towards the air/water interfacethan the polycarboxylate.

In addition, surface tension testing was conducted using the platemethod. In the plate method, testing was conducted by immersing aplatinum plate into solutions in order to determine the air/liquidinterfacial tensions of liquids. A Kruss K12 Tensiometer (Kruss GmbH,Hamburg, Germany) was used in order to determine surface tension changesof the tested liquids. This allowed for a better understanding of thechanges happening at the air/liquid interface and surfactantarrangement.

As seen in Table 1, the surface tension testing was conducted forsolutions of Foaming Agent 1B, i.e., Stepan Polystep B25. The tests werecarried out with and without further solution modification with 1 wt. %dodecanol. The solutions contained different concentrations (1000 ppmand 5000 ppm, respectively) of Foaming Agent 1B, i,e., Stepan PolystepB25. In addition, the tests were conducted with and without solutionmodification with polycarboxylate ether dispersant in the form ofEthacryl M™ (Coatex)in an amount of 0.1 wt. % (1000 ppm). The surfacetension values are in millinewtons per meter (mN/m).

TABLE 1 Surface Tension mN/m Foaming Agent Foaming Agent 1B modified 1Bwithout Ingredient with 1% Dodecanol Fatty Alcohol 1000 ppm of FoamingAgent 23.11 57.00 1B 1000 ppm of Foaming Agent 23.39 48.34 1B with PCE(1000 ppm) 5000 ppm of Foaming Agent 22.58 32.22 1B 5000 ppm of FoamingAgent 22.54 31.47 1B with PCE (1000 ppm)

The results of Table 1 show that the presence of fatty alcohol in theform of dodecanol was beneficial in producing a more robust (e.g.,strong) foam than without dodecanol. Also, it can be seen that there wasnot any deleterious effect on surface tension caused by the use ofpolycarboxylate dispersant when a fatty alcohol was used with thefoaming agent, indicating the stability (e.g., strength) of the foam.Surface tensions of dodecanol modified surfactant solutions decreased,when compared with unmodified surfactant. Lower surface tensiongenerally indicates higher surface activity and can allow for reductionin surfactant usage to achieve the same foaming properties.

Furthermore, degradation of the foam generated from the unstable FoamingAgents 1A and 1B was evaluated. The foaming agents were considered aloneand when the surfactant solution was modified with fatty alcohol as setforth in FIGS. 4 and 5. Degradation was determined by measuring the foamheight in mm with aging time.

As seen in FIGS. 4 and 5 modification of the surfactant solutions withfatty alcohols also influenced degradation. In FIG. 5, “1k” refers to1000 ppm of foaming agent in the solution. Foam heights were higher forall modified soaps, and the results show that modified soaps degrade ata slower pace than conventional foaming agents. A rapid decrease of foamheight indicates unstable bubbles and significant liquid drainage fromthe foam. In all cases, the soap solutions modified with fatty alcohollasted longer and did not degrade as quickly as conventional unmodifiedsoaps.

EXAMPLE 2

This example demonstrates the effect of fatty alcohols on the foamingproperties of foaming agents in wallboard manufacture.

Wallboard was prepared on a commercial manufacturing line. Each boardwas prepared from the formulation set forth in Table 2. The boards wereeach made with foaming agent in the form of an alkyl ether sulfate andalkyl sulfate at a ratio of 40:60, by soap blending with water andsubsequent foam generation and foam mixing with the gypsum slurry. Thealkyl ether sulfate was in the form of Geo Hyonic PFM 33, while thealkyl sulfate was in the than of Geo Hyonic 25 AS (both available fromGeo Specialty Chemicals).

The BMA was a ball milled accelerator, which contained gypsum and wasprepared by dry milling with dextrose. The dispersant was apolycarboxylate dispersant in the form of BASF Melflux 541, commerciallyavailable from BASF, Germany. The retarder was a 1% solution of anaqueous solution of the pentasodium salt ofdiethylenetriaminepentaacetie acid (Versenex™ 80, commercially availablefrom DOW Chemical Company, Midland, Mich.), and prepared by mixing 1part (weight) of Versenex™ 80 with 99 parts (weight) of water.

Dry and wet ingredients were introduced separately into a mixer to forma stucco slurry (sometimes called a gypsum slurry). The slurry wasdischarged onto a moving paper cover sheet traveling on a conveyor sothat slurry spread to form a core over the paper. A dense skim coat wasapplied onto the paper cover sheet with the use of a roller. Denseslurry traveled around the edges of the roller to form the edges of theboard. A second cover sheet was applied to the core to form a sandwichstructure of a board precursor in the form of a long, continuous ribbon.The ribbon was allowed to set, and was cut, kiln dried, and processed toform the final board product.

TABLE 2 Weight % (Based on Weight (lbs/MSF) weight of Stucco) Stucco1880 — Water 1223 65.05%  Dispersant (BASF 541) 3.2 0.17% Total soap 0.60.03% BMA 6 0.32% Starch (Acid Modified) 6.5 0.35% Retarder (Versenex)0.2 0.01% Glass Fiber 6 0.32% Board Weight 2240 —

Four types of board were made from the formulation of Table 2, with thedifference relating to the presence of a long chain alcohol with thefoaming agent. Board 2A was a control and did not include anymodification of the foaming agent with fatty alcohol. Board 2B wasprepared with foaming agent that included 1% of 1-dodecanol, added tothe foaming agent. Board 2C was prepared with foaming agent thatincluded 1% of 1-decanol. Board 2D was prepared with foaming agent thatincluded 1% of 1-octanol. The foaming agents were prepared with the aidof a foam generating apparatus by high shear mixing of soap solutionwith pressurized air and introduced to the slurry outside of the mainmixer, before the slurry outlet.

Images taken from optical microscope at 20 × magnification were takenfrom the core of each type of hoard. A total of nine optical microscopyimages were taken from each of Boards 2A-2D. The nine images from eachboard were taken from nine different points in the same board core andthree were randomly selected for each board, which are presented asexamples of cores in FIGS. 6A to 9C. FIGS. 6A-6C are the images fromControl Board 2A. FIGS. 7A-7C are images from Board 2B. FIGS. 8A-8C areimages from Board 2G. FIGS. 9A-9C are images from Board 2D. As seen inthese FIGS., the core structure was influenced after the introduction ofsoap modifiers. As shown in FIGS. 6A-6C, the core structure of ControlBoard 2A has a significant number of larger voids, while Board 2B (FIGS.7A-7C) and Board 2D (FIGS. 9A-9C) showed a reduction of size of thelarger voids and reduced the overall void size, while Board 2C (FIGS.8A-8C) showed an increase of the void size.

Six images per condition were analyzed. The images randomly selectedfrom each experimental condition for void analysis (i.e., FIGS. 6A-6C,7A-7C, 8A-8C, 9A-9C,) were analyzed with the aid of Clemex Vision PE,available from Clemex Technologies, Inc., Longueuil, Quebec. For eachimage, void (bubble) size diameter was manually measured for each void.A distribution was provided by the software. A summary of the resultsare reported in Table 3.

TABLE 3 Void Size (μm) Arithmetic Volumetric Average Average Board 2A(Control) (Regular 234 819 soap blend) Board 2B 168 627 (Soap blendmodified with 1% of 1-Dodecanol) Board 2C 245 1092 (Soap blend modifiedwith 1% of 1-Decanol) Board 2D 188 739 (Soap blend modified with 1% of1-Octanol)

The arithmetic average was determined by the software and indicates thearithmetic average of void diameter (in micrometers) from all voidswithin the board. The volumetric average was determined from thedistribution diagrams developed by the software and indicates theaverage void sizes weighted by volume.

Furthermore, FIGS. 10-13 are bar graphs illustrating volumetricdistributions of each of Boards 2A (FIG. 10), 2B (FIG. 11), 2C (FIG.12), and 2D (FIG. 13). The bar graphs show the volumetric frequency ofvoids as a function of void size in micrometers.

As seen from Table 3 and FIGS. 10-13, the voids in the Control Board 2Awere generally larger and more dispersed, while the voids of Boards 2B,and 2D were smaller and narrower in distribution. The voids of controlboard were larger and more evenly distributed. The distribution of thevoids in the Control Board 2A was bimodal, while the distribution inBoards 2B and 2D was monomodal and Gaussian.

These results demonstrate that surfactant (soap) modification in foamingagent is sufficient to induce void size distribution changes inwallboard, without otherwise changing the formulation or surfactantdosage. These results further show that a more favored distribution(narrower or wider) can be easily achieved without the need of a newsurfactant blend.

EXAMPLE 3

This example illustrates that soap modifications can reduce the surfacetension of foaming agent blends. In particular, surface tension testingwas conducted using the plate method, as described in Example 1, with aKruss K12 Tensiometer.

The surface tension testing was conducted for solutions of Foaming Agent3A, i.e., Stepan B25, and Foaming Agent 3B, i.e., Hyonic 25AS. The testsfor each foaming agent were carried out without further solutionmodification (control), and also with further solution modification with1 wt. % dodecanol, 1 wt. % decanol, and 1 wt. % octanol. The solutionscontained different concentrations (2000 ppm, 1000 ppm and 500 ppm,respectively) of the foaming agents. The results are shown in Table 4.

TABLE 4 Surface tension mN/m 500 ppm 1000 ppm 2000 ppm Foaming Agent 3A64 54 45 (Polystep B25) Foaming Agent 3A with 1- 28 25 23 DodecanolFoaming Agent 3A with 1- 41 36 27 Decanol Foaming Agent 3A with 1- 53 4638 Octanol Foaming Agent 3B 60 51 41 (Hyonic 25AS) Foaming Agent 3B with1- 23.1 23.8 22.5 Dodecanol Foaming Agent 3B with 1- 50.4 41.5 31.0Decanol Foaming Agent 3B with 1- 57.9 50.1 39.6 Octanol

The results of Table 4 show that the presence of fatty alcohol wasbeneficial in producing a more surface active soap blend. For example,it can be seen that surface tension of modified soap was reduced,indicating the stability (e.g., strength) of the foam was improved.Surface tension of alcohol -modified surfactant solutions decreased,when compared with unmodified surfactant. Lower surface tensiongenerally indicates higher surface activity and can allow for reductionin surfactant usage to achieve the same foaming properties.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto he incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and “at least one” andsimilar referents in the context of describing the invention (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The use of the term “at least one”followed by a list of one or more items (for example, “at least one of Aand B”) is to be construed to mean one item selected from the listeditems (A or B) or any combination of two or more of the listed items (Aand B), unless otherwise indicated herein or clearly contradicted bycontext. As used herein, it will be understood that the term “bondingrelation” does not necessarily mean that two layers are in immediatecontact. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Also, everywhere “comprising”(or its equivalent) is recited, the “comprising” is considered toincorporate “consisting essentially of” and “consisting of.” Thus, anembodiment “comprising” (an) element(s) supports embodiments “consistingessentially of” and “consisting of” the recited element(s). Everywhere“consisting essentially of” is recited is considered to incorporate“consisting of.” Thus, an embodiment “consisting essentially of” (an)element(s) supports embodiments “consisting of” the recited element(s).Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention unless otherwise claimed. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A method of making a foamed cementitious board comprising: (a)blending a first amount of a first foaming agent, a second amount of asecond foaming agent, and a third amount of a fatty alcohol to form anaqueous blended stream, wherein the first, second, and third amounts arein a first weight ratio; (b) controllably changing the first, second,and/or third amounts to form a second weight ratio, which is differentthan the first weight ratio; (c) inserting air into the blended streamto form foam; (d) mixing at least water, cementitious material, and thefoam to form a slurry; (e) disposing the slurry between a first coversheet and a second cover sheet to form a board precursor; (f) cuttingthe board precursor into a board; and (g) drying the board.
 2. Themethod of claim 1, wherein a process controller is used to controllablychange the first, second, and/or third amounts.
 3. The method of claim2, wherein the first, second, and third amounts are controlled by a flowmetering system, and wherein the process controller communicates withthe flow metering system to adjust one or more of the first, second, andthird amounts.
 4. The method of claim 3, wherein the flow meteringsystem comprises at least one pump operatively associated with valvesfor controlling flow of each of the first foaming agent, second foamingagent, and fatty alcohol into the aqueous blended stream.
 5. The methodof claim wherein the first foaming agent is a stable soap and the secondfoaming agent is an unstable soap.
 6. The method of claim 1, wherein thefatty alcohol is a C₆-C₂₀ fatty alcohol.
 7. The method of claim 1,wherein the fatty alcohol is octanol, nonanol, decanol, undecanol,dodecanol, or any combination thereof.
 8. The method of claim 1, whereinthe slurry further comprises a dispersant.
 9. The method of claim 1,wherein the slurry further comprises a non-migrating starch thatincreases the strength of the board compared to the same board preparedwithout the starch.
 10. The method of claim 1, wherein the slurryfurther comprises a polyphosphate.
 11. The method of claim 1, whereinthe board has a density of about 17 pcf to about 31 pcf.
 12. The methodof claim 4, wherein the stable foaming agent is combined with the fattyalcohol prior to addition of the unstable foaming agent.
 13. The methodof claim 4, wherein the unstable foaming agent is combined with thefatty alcohol prior to addition of the stable foaming agent.
 14. Asystem for forming a foam, the system comprising: (a) a foam generator;(b) an air supply conduit for introducing air into the foam generator;(c) a flow metering system configured to introduce a first amount of afoaming agent, a second amount of a second foaming agent, and a thirdamount of a fatty alcohol, irrespective of order, directly or indirectlyinto the foam generator; (d) a controller which communicates with theflow metering system to selectively change the relative amounts of firstfoaming agent, second foaming agent, and fatty alcohol that areintroduced directly or indirectly into the foam generator.
 15. Thesystem of claim 14, wherein the fatty alcohol is a C₆-C₂₀ fatty alcohol.16. The system of claim 14, wherein the fatty alcohol is octanol,nonanol, decanol, undecanol, dodecanol, or any combination thereof. 17.The system of claim 14, wherein the foaming agent comprises an alkylsulfate surfactant.
 18. The system of claim 14, wherein the firstfoaming agent is a stable soap and the second foaming agent is anunstable soap.
 19. The system of claim 14, wherein the flow meteringsystem comprises at least one pump operatively associated with valvesfor controlling flow of each of the first foaming agent, second foamingagent, and fatty alcohol into a blended stream conduit in fluidcommunication with the foam generator.
 20. A system for forming a foam,the system comprising: (a) a flow metering system comprising at leastone pump operatively associated with one or more valve for controllingflow of a first foaming agent, a second foaming agent, and fatty alcoholinto a blended stream conduit, irrespective of order; (b) a controllerwhich communicates with the flow metering system to selectively changethe relative amounts of first foaming agent, second foaming agent, andfatty alcohol that are introduced into the blended stream conduit; (c) afoam generator in fluid communication with the blended stream conduit;and (d) an air supply conduit for introducing air into the foamgenerator.